@article{li_zhong_cheng_chen_wang_liu_sun_zhang_liu_2024, title={Chiral phonon activated spin Seebeck effect in chiral materials}, volume={67}, ISSN={["1869-1927"]}, DOI={10.1007/s11433-023-2281-x}, number={3}, journal={SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY}, author={Li, Xiao and Zhong, Jinxin and Cheng, Jinluo and Chen, Hao and Wang, Huiqian and Liu, Jun and Sun, Dali and Zhang, Lifa and Liu, Jun}, year={2024}, month={Mar} }
 @article{xiong_christy_dong_comstock_sun_li_cahoon_yang_zhang_2024, title={Combinatorial split-ring and spiral metaresonator for efficient magnon-photon coupling}, volume={21}, ISSN={["2331-7019"]}, DOI={10.1103/PhysRevApplied.21.034034}, number={3}, journal={PHYSICAL REVIEW APPLIED}, author={Xiong, Yuzan and Christy, Andrew and Dong, Yun and Comstock, Andrew H. and Sun, Dali and Li, Yi and Cahoon, James F. and Yang, Binbin and Zhang, Wei}, year={2024}, month={Mar} }
 @article{sun_park_comstock_mcconnell_chen_zhang_beratan_you_hoffmann_yu_et al._2024, title={Inverse chirality-induced spin selectivity effect in chiral assemblies of <i>π</i>-conjugated polymers}, volume={3}, ISSN={["1476-4660"]}, DOI={10.1038/s41563-024-01838-8}, journal={NATURE MATERIALS}, author={Sun, Rui and Park, Kyung Sun and Comstock, Andrew H. and Mcconnell, Aeron and Chen, Yen-Chi and Zhang, Peng and Beratan, David and You, Wei and Hoffmann, Axel and Yu, Zhi-Gang and et al.}, year={2024}, month={Mar} }
 @article{yang_qiu_li_xue_liu_sun_yang_gai_wei_comstock_et al._2023, title={Anisotropic Nonlocal Damping in Ferromagnet/α -GeTe Bilayers Enabled by Splitting Energy Bands}, volume={131}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.131.186703}, abstractNote={The understanding and manipulation of anisotropic Gilbert damping is crucial for both fundamental research and versatile engineering and optimization. Although several works on anisotropic damping have been reported, no direct relationship between the band structure and anisotropic damping was established. Here, we observed an anisotropic damping in Fe/GeTe manipulated by the symmetric band structures of GeTe via angle-resolved photoemission spectroscopy. Moreover, the anisotropic damping can be modified by the symmetry of band structures. Our Letter provides insightful understandings of the anisotropic Gilbert damping in ferromagnets interfaced with Rashba semiconductors and suggests the possibility of manipulating the Gilbert damping by band engineering.}, number={18}, journal={PHYSICAL REVIEW LETTERS}, author={Yang, Xu and Qiu, Liang and Li, Yan and Xue, Hao-Pu and Liu, Jia-Nan and Sun, Rui and Yang, Qing-Lin and Gai, Xue-Song and Wei, Yan-Sheng and Comstock, Andrew H. and et al.}, year={2023}, month={Nov} }
 @article{lu_he_wu_qi_wang_sun_shao_qiao_zhang_sun_et al._2023, title={Chiral Ruthenium Halide Semiconductor with Strong Antiferromagnetic Coupling}, volume={9}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202308862}, abstractNote={Chiral hybrid organic–inorganic metal halides have attracted wide attention owing to their superior chiroptoelectronic and chirospintronic properties. Here, a new class of chiral lead‐free metal halides, (R/S‐MBA)3Ru2Br9 (MBA = methylbenzylammonium), with unique magnetic properties is reported. (R/S‐MBA)3Ru2Br9 is composed of a surface‐shared octahedron dimer separated by chiral cations and crystallizes into the Sohncke space group of P212121. The crystal structures, chiroptical, magnetic properties, and magnetic circular dichroism of (R/S‐MBA)3Ru2Br9 are systematically investigated. Owing to the strong antiferromagnetic coupling between the Ru atom through bromine bridge in the [Ru2Br9]3− dimer and the weak ferromagnetic coupling between the neighboring [Ru2Br9]3− dimer, (R/S‐MBA)3Ru2Br9 exhibits antiferromagnetic property with Néel temperature at 7 K. Considering the unique magnetic property of ruthenium, together with the rapid progress of antiferromagnetic spintronics and optospintronics recently, this work provides a novel multifunctional lead‐free chiral magnetic candidate toward chiral optoelectronics and antiferromagnetic spintronics.}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Lu, Haolin and He, Tengfei and Wu, Haolin and Qi, Fenglian and Wang, Hebin and Sun, Bing and Shao, Tianyin and Qiao, Tianjiao and Zhang, Hao-Li and Sun, Dali and et al.}, year={2023}, month={Sep} }
 @article{kim_vetter_yan_yang_wang_sun_yang_comstock_li_zhou_et al._2023, title={Chiral-phonon-activated spin Seebeck effect}, volume={2}, ISSN={["1476-4660"]}, url={http://dx.doi.org/10.1038/s41563-023-01473-9}, DOI={10.1038/s41563-023-01473-9}, abstractNote={Utilization of the interaction between spin and heat currents is the central focus of the field of spin caloritronics. Chiral phonons possessing angular momentum arising from the broken symmetry of a non-magnetic material create the potential for generating spin currents at room temperature in response to a thermal gradient, precluding the need for a ferromagnetic contact. Here we show the observation of spin currents generated by chiral phonons in a two-dimensional layered hybrid organic-inorganic perovskite implanted with chiral cations when subjected to a thermal gradient. The generated spin current shows a strong dependence on the chirality of the film and external magnetic fields, of which the coefficient is orders of magnitude larger than that produced by the reported spin Seebeck effect. Our findings indicate the potential of chiral phonons for spin caloritronic applications and offer a new route towards spin generation in the absence of magnetic materials.}, journal={NATURE MATERIALS}, publisher={Springer Science and Business Media LLC}, author={Kim, Kyunghoon and Vetter, Eric and Yan, Liang and Yang, Cong and Wang, Ziqi and Sun, Rui and Yang, Yu and Comstock, Andrew H. and Li, Xiao and Zhou, Jun and et al.}, year={2023}, month={Feb} }
 @article{xue_sun_yang_comstock_liu_ge_liu_wei_yang_gai_et al._2023, title={Dual Topology of Dirac Electron Transport and Photogalvanic Effect in Low-Dimensional Topological Insulator Superlattices}, volume={1}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202208343}, abstractNote={Dual topological insulators, simultaneously protected by time‐reversal symmetry and crystalline symmetry, open great opportunities to explore different symmetry‐protected metallic surface states. However, the conventional dual topological states located on different facets hinder integration into planar opto‐electronic/spintronic devices. Here, dual topological superlattices (TSLs) Bi2Se3‐(Bi2/Bi2Se3)N with limited stacking layer number N are constructed. Angle‐resolved photoelectron emission spectra of the TSLs identify the coexistence and adjustment of dual topological surface states on Bi2Se3 facet. The existence and tunability of spin‐polarized dual‐topological bands with N on Bi2Se3 facet result in an unconventionally weak antilocalization effect (WAL) with variable WAL coefficient α (maximum close to 3/2) from quantum transport experiments. Most importantly, it is identified that the spin‐polarized surface electrons from dual topological bands exhibit circularly and linearly polarized photogalvanic effect (CPGE and LPGE). It is anticipated that the stacked dual‐topology and stacking layer number controlled bands evolution provide a platform for realizing intrinsic CPGE and LPGE. The results show that the surface electronic structure of the dual TSLs is highly tunable and well‐regulated for quantum transport and photoexcitation, which shed light on engineering for opto‐electronic/spintronic applications.}, journal={ADVANCED MATERIALS}, author={Xue, Hao-Pu and Sun, Rui and Yang, Xu and Comstock, Andrew and Liu, Yangrui and Ge, Binghui and Liu, Jia-Nan and Wei, Yan-Sheng and Yang, Qing-Lin and Gai, Xue-Song and et al.}, year={2023}, month={Jan} }
 @article{li_comstock_mcconnell_li_yun_sun_xu_2023, title={Giant interfacial spin Hall angle from Rashba-Edelstein effect revealed by the spin Hall Hanle process}, volume={108}, ISSN={["2469-9969"]}, url={https://doi.org/10.1103/PhysRevB.108.L241403}, DOI={10.1103/PhysRevB.108.L241403}, abstractNote={The Rashba-Edelstein effect (REE), which generates interfacial spin polarization and subsequent spin current, is a compelling spin-charge conversion mechanism for spintronics applications, since it is not limited by the elemental spin-orbit coupling. In this work, we demonstrate REE at Pt/ferroelectric interfaces using the recently elucidated spin-Hall Hanle effects (SHHE), in which a Larmor precession of spin polarization in a diffusion process from the interface manifest as magnetoresistance and Hall effect. We show that REE leads to a three-fold enhancement of the effective spin Hall angle in ferroelectric interface Pt/h-LuFeO3 compared to that of Pt /Al2O3, although the difference in the spin relaxation time is negligible. Modeling using SHHEs involving REE as an additional source of interfacial polarization suggests that REE can lead to an interfacial spin Hall angle (~0.3) that is one order of magnitude larger than the bulk value of Pt. Our results demonstrate that a ferroelectric interface can produce large spin-charge conversion and that SHHEs are a sensitive tool for characterizing interfacial spin transport properties.}, number={24}, journal={PHYSICAL REVIEW B}, author={Li, Jing and Comstock, Andrew H. and Mcconnell, Aeron and Li, Xin and Yun, Yu and Sun, Dali and Xu, Xiaoshan}, year={2023}, month={Dec} }
 @article{comstock_chou_wang_wang_song_sklenar_amassian_zhang_lu_liu_et al._2023, title={Hybrid magnonics in hybrid perovskite antiferromagnets}, volume={14}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-023-37505-w}, DOI={10.1038/s41467-023-37505-w}, abstractNote={Abstract Hybrid magnonic systems are a newcomer for pursuing coherent information processing owing to their rich quantum engineering functionalities. One prototypical example is hybrid magnonics in antiferromagnets with an easy-plane anisotropy that resembles a quantum-mechanically mixed two-level spin system through the coupling of acoustic and optical magnons. Generally, the coupling between these orthogonal modes is forbidden due to their opposite parity. Here we show that the Dzyaloshinskii–Moriya-Interaction (DMI), a chiral antisymmetric interaction that occurs in magnetic systems with low symmetry, can lift this restriction. We report that layered hybrid perovskite antiferromagnets with an interlayer DMI can lead to a strong intrinsic magnon-magnon coupling strength up to 0.24 GHz, which is four times greater than the dissipation rates of the acoustic/optical modes. Our work shows that the DMI in these hybrid antiferromagnets holds promise for leveraging magnon-magnon coupling by harnessing symmetry breaking in a highly tunable, solution-processable layered magnetic platform.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Comstock, Andrew H. and Chou, Chung-Tao and Wang, Zhiyu and Wang, Tonghui and Song, Ruyi and Sklenar, Joseph and Amassian, Aram and Zhang, Wei and Lu, Haipeng and Liu, Luqiao and et al.}, year={2023}, month={Apr} }
 @article{li_draher_comstock_xiong_haque_easy_qian_polakovic_pearson_divan_et al._2023, title={Probing intrinsic magnon bandgap in a layered hybrid perovskite antiferromagnet by a superconducting resonator}, volume={5}, ISSN={["2643-1564"]}, DOI={10.1103/PhysRevResearch.5.043031}, abstractNote={Coherent interactions between different magnetic excitations can lead to formation of magnon band gaps and hybrid magnon modes, which can find their applications in magnonic devices and coherent information processing. In this work, we probe the intrinsic magnon band gap of a layered hybrid perovskite antiferromagnet by its strong coupling to a superconducting resonator. The pronounced temperature tunability of the magnon band gap location allows us to set the photon mode within the gap, leading to a reduction of effective magnon-photon coupling and eventually the disappearance of magnon-photon hybridization. When the resonator mode falls into the magnon band gap, the resonator damping rate increases due to the nonzero coupling to the detuned magnon mode. This allows for quantification of the magnon band gap using an analytical model. Our work brings new opportunities in controlling coherent information processing with quantum properties in complex magnetic materials.}, number={4}, journal={PHYSICAL REVIEW RESEARCH}, author={Li, Yi and Draher, Timothy and Comstock, Andrew H. and Xiong, Yuzan and Haque, Md Azimul and Easy, Elham and Qian, Jiangchao and Polakovic, Tomas and Pearson, John E. and Divan, Ralu and et al.}, year={2023}, month={Oct} }
 @article{frick_sridhar_khansari_comstock_norman_o'donnell_maggard_sun_dougherty_2023, title={Spreading resistance effects in tunneling spectroscopy of α-RuCl3 and Ir0.5Ru0.5Cl3}, volume={108}, ISSN={["2469-9969"]}, url={https://doi.org/10.1103/PhysRevB.108.245410}, DOI={10.1103/PhysRevB.108.245410}, abstractNote={The Mott insulating state is the progenitor of many interesting quantum phases of matter including the famous high-temperature superconductors and quantum spin liquids. A recent candidate for novel spin liquid phenomena is $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$, a layered honeycomb Mott insulator whose electronic structure has been a source of mystery. In particular, scanning tunneling spectroscopy has indicated a Mott gap in $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$ that is much lower than the 2-eV value observed in photoemission measurements. Here, we show that the origin of this discrepancy is a spreading resistance artifact associated with tunneling into highly resistive materials by comparing with prior experiments and numerical modeling. A similar phenomenon is also observed in a substitutional alloy, ${\mathrm{Ir}}_{0.5}{\mathrm{Ru}}_{0.5}{\mathrm{Cl}}_{3}$, that has a higher resistivity than the parent compound. While the tunneling measurements cannot be used to accurately measure the sample density of states for these materials, we can take advantage of the spreading resistance sensitivity to quantify the anisotropic resistivity of these layered materials and connect to previous macroscopic transport observations.}, number={24}, journal={PHYSICAL REVIEW B}, author={Frick, Jordan R. and Sridhar, Samanvitha and Khansari, Ario and Comstock, Andrew H. and Norman, Elizabeth and O'Donnell, Shaun and Maggard, Paul A. and Sun, Dali and Dougherty, Daniel B.}, year={2023}, month={Dec} }
 @article{wang_li_ardekani_serrano-lujan_wang_ramezani_wilmington_chauhan_epps_darabi_et al._2023, title={Sustainable materials acceleration platform reveals stable and efficient wide-bandgap metal halide perovskite alloys}, volume={6}, ISSN={["2590-2385"]}, DOI={10.1016/j.matt.2023.06.040}, abstractNote={The vast chemical space of emerging semiconductors, like metal halide perovskites, and their varied requirements for semiconductor applications have rendered trial-and-error environmentally unsustainable. In this work, we demonstrate RoboMapper, a materials acceleration platform (MAP), that achieves 10-fold research acceleration by formulating and palletizing semiconductors on a chip, thereby allowing high-throughput (HT) measurements to generate quantitative structure-property relationships (QSPRs) considerably more efficiently and sustainably. We leverage the RoboMapper to construct QSPR maps for the mixed ion FA1−yCsyPb(I1−xBrx)3 halide perovskite in terms of structure, bandgap, and photostability with respect to its composition. We identify wide-bandgap alloys suitable for perovskite-Si hybrid tandem solar cells exhibiting a pure cubic perovskite phase with favorable defect chemistry while achieving superior stability at the target bandgap of ∼1.7 eV. RoboMapper’s palletization strategy reduces environmental impacts of data generation in materials research by more than an order of magnitude, paving the way for sustainable data-driven materials research.}, number={9}, journal={MATTER}, author={Wang, Tonghui and Li, Ruipeng and Ardekani, Hossein and Serrano-Lujan, Lucia and Wang, Jiantao and Ramezani, Mahdi and Wilmington, Ryan and Chauhan, Mihirsinh and Epps, Robert W. and Darabi, Kasra and et al.}, year={2023}, month={Sep}, pages={2963–2986} }
 @article{negi_rodriguez_zhang_comstock_yang_sun_jiang_kumah_hu_liu_2023, title={Thickness-Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single-Crystalline Barium Titanate}, volume={4}, ISSN={["2198-3844"]}, url={https://doi.org/10.1002/advs.202301273}, DOI={10.1002/advs.202301273}, abstractNote={Nanosized perovskite ferroelectrics are widely employed in several electromechanical, photonics, and thermoelectric applications. Scaling of ferroelectric materials entails a severe reduction in the lattice (phonon) thermal conductivity, particularly at sub‐100 nm length scales. Such thermal conductivity reduction can be accurately predicted using the information of phonon mean free path (MFP) distribution. The current understanding of phonon MFP distribution in perovskite ferroelectrics is still inconclusive despite the critical thermal management implications. Here, high‐quality single‐crystalline barium titanate (BTO) thin films, a representative perovskite ferroelectric material, are grown at several thicknesses. Using experimental thermal conductivity measurements and first‐principles based modeling (including four‐phonon scattering), the phonon MFP distribution is determined in BTO. The simulation results agree with the measured thickness‐dependent thermal conductivity. The results show that the phonons with sub‐100 nm MFP dominate the thermal transport in BTO, and phonons with MFP exceeding 10 nm contribute ≈35% to the total thermal conductivity, in significant contrast to previously published experimental results. The experimentally validated phonon MFP distribution is consistent with the theoretical predictions of other complex crystals with strong anharmonicity. This work paves the way for thermal management in nanostructured and ferroelectric‐domain‐engineered systems for oxide perovskite‐based functional materials.}, journal={ADVANCED SCIENCE}, author={Negi, Ankit and Rodriguez, Alejandro and Zhang, Xuanyi and Comstock, Andrew H. H. and Yang, Cong and Sun, Dali and Jiang, Xiaoning and Kumah, Divine and Hu, Ming and Liu, Jun}, year={2023}, month={Apr} }
 @article{corzo_wang_gedda_yengel_khan_li_niazi_huang_kim_baran_et al._2022, title={A Universal Cosolvent Evaporation Strategy Enables Direct Printing of Perovskite Single Crystals for Optoelectronic Device Applications}, volume={34}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.202109862}, DOI={10.1002/adma.202109862}, abstractNote={Solution‐processed metal halide perovskite (MHP) single crystals (SCs) are in high demand for a growing number of printed electronic applications due to their superior optoelectronic properties compared to polycrystalline thin films. There is an urgent need to make SC fabrication facile, scalable, and compatible with the printed electronic manufacturing infrastructure. Here, a universal cosolvent evaporation (CSE) strategy is presented by which perovskite SCs and arrays are produced directly on substrates via printing and coating methods within minutes at room temperature from drying droplets. The CSE strategy successfully guides the supersaturation via controlled drying of droplets to suppress all crystallization pathways but one, and is shown to produce SCs of a wide variety of 3D, 2D, and mixed‐cation/halide perovskites with consistency. This approach works with commonly used precursors and solvents, making it universal. Importantly, the SC consumes the precursor in the droplet, which enables the large‐scale fabrication of SC arrays with minimal residue. Direct on‐chip fabrication of 3D and 2D perovskite photodetector devices with outstanding performance is demonstrated. The approach shows that any MHP SC can now be manufactured on substrates using precision printing and scalable, high‐throughput coating methods.}, number={9}, journal={Advanced Materials}, publisher={Wiley}, author={Corzo, Daniel and Wang, Tonghui and Gedda, Murali and Yengel, Emre and Khan, Jafar I and Li, Ruipeng and Niazi, Muhammad Rizwan and Huang, Zhengjie and Kim, Taesoo and Baran, Derya and et al.}, year={2022}, month={Jan}, pages={2109862} }
 @article{xue_wang_comstock_wang_sung_williams_sun_liu_lu_2022, title={Chemical Control of Magnetic Ordering in Hybrid Fe-CI Layered Double Perovskites}, volume={34}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.2c00163}, DOI={10.1021/acs.chemmater.2c00163}, abstractNote={Recent discoveries of novel physics in two-dimensional (2D) magnetic materials have sparked the search of new layered magnetic semiconductors. Compared to the traditional inorganic 2D van der Waals crystals, hybrid organic–inorganic metal–halide frameworks offer significantly enhanced chemical and structural versatility, where their optical, electronic, and magnetic properties can be readily modulated with both organic and inorganic components. Here, we reported a series of new Fe–Cl-based layered double perovskites LnMIMIIICl8, [n = 4, L = phenylethylammonium or chiral R-(+)-β-methylphenethylammonium and n = 2, L = 1,4-butanediammonium; MI = Ag/Na; MIII = Fe/In]. UV–vis measurements show that their optical band gaps are highly tunable by varying the organic cations, MI ion, and MIII ion. Magnetic susceptibility measurements suggest an antiferromagnetic coupling between the nearest FeIII–FeIII, where the Curie–Weiss temperature, Néel temperature, and frustration factors can be easily modulated with their compositions and dimensionality. Our study demonstrates the rich and interesting magnetic properties in these layered transition-metal–halide double perovskites and paves the way for design of multifunctional magnetic materials.}, number={6}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Xue, Jie and Wang, Ziyu and Comstock, Andrew and Wang, Zhiyu and Sung, Herman H. Y. and Williams, Ian D. and Sun, Dali and Liu, Junwei and Lu, Haipeng}, year={2022}, month={Mar}, pages={2813–2823} }
 @article{li_comstock_sun_xu_2022, title={Comprehensive demonstration of spin Hall Hanle effects in epitaxial Pt thin films}, url={https://doi.org/10.1103/PhysRevB.106.184420}, DOI={10.1103/PhysRevB.106.184420}, abstractNote={We demonstrate a nonlinear Hall effect due to the boundary spin accumulation in Pt films grown on Al2O3 substrates. This Hall effect and the previously demonstrated Hanle magnetoresistance provide a complete picture of the spin-precession control of the spin and charge transport at the boundary of a spin-orbit coupled material, which we refer to as spin-Hall Hanle effects (SHHE). We also show that the SHHE can be employed to measure the spin diffusion length, the spin-Hall angle, and the spin relaxation time of heavy metal without the need of magnetic interface or the input from other measurements. The comprehensive demonstration of SHHE in such a simple system suggests they may be ubiquitous and needs to be considered for unravelling the spin and charge transport in more complex thin film structures of spin-orbit coupled materials.}, journal={Physical Review B}, author={Li, Jing and Comstock, Andrew H. and Sun, Dali and Xu, Xiaoshan}, year={2022}, month={Nov} }
 @article{comstock_biliroglu_seyitliyev_mcconnell_vetter_reddy_kirste_szymanski_sitar_collazo_et al._2022, title={Spintronic Terahertz Emission in Ultrawide Bandgap Semiconductor/Ferromagnet Heterostructures}, volume={10}, ISSN={["2195-1071"]}, DOI={10.1002/adom.202201535}, abstractNote={Recent successful integration of semiconductors into spintronic THz emitters has demonstrated a new pathway of control over terahertz (THz) radiation through ultrafast demagnetization dynamics. Here, the spintronic THz emission from different ultrawide bandgap (UWBG) semiconductors interfaced with ferromagnets is studied. The authors show that the Schottky barrier in the UWBG semiconductor AlN acts as a spin filter that increases the polarization of the spin current injected from the ferromagnet. Furthermore, the authors show that the two‐dimensional electron gas at the interface between Al0.25Ga0.75N and GaN enhances the magnitude of the emitted radiation due to the high spin‐to‐charge conversion efficiency induced by the Rashba effect that results in a hallmark asymmetry in emission amplitude. The results provide a framework for future engineering of semiconducting/ferromagnet heterostructures for ultrafast communications technologies beyond 5G.}, journal={ADVANCED OPTICAL MATERIALS}, author={Comstock, Andrew and Biliroglu, Melike and Seyitliyev, Dovletgeldi and McConnell, Aeron and Vetter, Eric and Reddy, Pramod and Kirste, Ronny and Szymanski, Dennis and Sitar, Zlatko and Collazo, Ramon and et al.}, year={2022}, month={Oct} }
 @article{mclaughlin_pan_sun_kwon_vardeny_2022, title={Study of Photocarriers Lifetime Distribution in a-Si:H via Magneto-photoconductivity and Magneto-Photoluminescence}, volume={5}, ISSN={["2195-1071"]}, DOI={10.1002/adom.202200499}, abstractNote={Herein, the magneto‐photoluminescence (MPL) of localized photocarriers and magneto‐photoconductivity (MPC) of delocalized photocarriers in amorphous hydrogenated silicon (a‐Si:H) films and devices, respectively, are investigated. Both responses are caused by mixing of spin sublevels in the photogenerated electron–hole (e–h) pairs that alters their recombination and dissociation rates. The spin mixing occurs by a combination of hyperfine interaction (HFI) between spin ½ photocarriers and neighboring 29Si and 1H nuclei, and the Δg mechanism which originates from a difference in the Landé g‐factors of electrons and holes. The existing disorder in a‐Si:H films leads to dispersive field response that is described by a unique dispersive parameter α < 1, from which the e–h lifetime distribution, g(τ) is obtained. The mean e–h lifetime is found to be ≈12 ns for the high‐energy, relatively delocalized photocarriers generating the photocurrent, as compared to ≈200 ps for the lower energy, trapped e–h pairs which yield photoluminescence. The MPL(B) and MPC(B) responses in a‐Si:H subjected to prolonged illumination that causes Staebler–Wronski type degradation, and subsequent annealing are studied. The illumination‐induced photocarrier localization that enhances the HFI component is found, which dramatically decreases upon annealing; this method can assess optoelectronic device degradation.}, journal={ADVANCED OPTICAL MATERIALS}, author={McLaughlin, Ryan and Pan, Xin and Sun, Dali and Kwon, Ohyun and Vardeny, Zeev Valy}, year={2022}, month={May} }
 @article{cong_vetter_yan_li_zhang_xiong_qu_schaller_hoffmann_kemper_et al._2021, title={Coherent control of asymmetric spintronic terahertz emission from two-dimensional hybrid metal halides}, volume={12}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-021-26011-6}, DOI={10.1038/s41467-021-26011-6}, abstractNote={Next-generation terahertz (THz) sources demand lightweight, low-cost, defect-tolerant, and robust components with synergistic, tunable capabilities. However, a paucity of materials systems simultaneously possessing these desirable attributes and functionalities has made device realization difficult. Here we report the observation of asymmetric spintronic-THz radiation in Two-Dimensional Hybrid Metal Halides (2D-HMH) interfaced with a ferromagnetic metal, produced by ultrafast spin current under femtosecond laser excitation. The generated THz radiation exhibits an asymmetric intensity toward forward and backward emission direction whose directionality can be mutually controlled by the direction of applied magnetic field and linear polarization of the laser pulse. Our work demonstrates the capability for the coherent control of THz emission from 2D-HMHs, enabling their promising applications on the ultrafast timescale as solution-processed material candidates for future THz emitters.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Cong, Kankan and Vetter, Eric and Yan, Liang and Li, Yi and Zhang, Qi and Xiong, Yuzan and Qu, Hongwei and Schaller, Richard D. and Hoffmann, Axel and Kemper, Alexander F. and et al.}, year={2021}, month={Sep} }
 @article{zhang_cao_huang_danilov_chung_sun_yang_2021, title={Gamma-Ray Detection Using Bi-Poor Cs2AgBiBr6 Double Perovskite Single Crystals}, volume={9}, ISSN={["2195-1071"]}, url={https://doi.org/10.1002/adom.202001575}, DOI={10.1002/adom.202001575}, abstractNote={Lead halide perovskites have recently attracted intensive attention as competitive alternative candidates of legacy compound materials CdTe, CdZnTe, and TlBr for high sensitivity energy‐resolving gamma‐ray detection at room temperature. However, the use of lead in these lead halide perovskites, which is necessary for increasing the stopping power of gamma radiation, poses a serious environmental concern due to the high toxicity of lead. In this regard, environmental‐friendly perovskite‐based gamma‐ray detector materials with key energy‐resolving capabilities are highly desired. Here, the gamma energy‐resolving performance of a new class of all‐inorganic and lead‐free Cs2AgBiBr6 double perovskite single crystals (SCs) is reported. Two types of Cs2AgBiBr6 SCs, prepared by Bi‐normal and Bi‐poor precursor solutions, respectively, have been grown. Their mobilities and response to gamma radiation are presented. Density of trap states in Bi‐poor Cs2AgBiBr6 SCs (2.65 × 109 cm−3) is one order of magnitude lower than that in Bi‐normal Cs2AgBiBr6 SCs (3.85 × 1010 cm−3). Using laser‐induced photocurrent measurements, the obtained mobility–lifetime (μ–τ) product in Bi‐poor Cs2AgBiBr6 SCs is 1.47 × 10−3 cm2 V−1, indicating their great potentials for gamma‐ray detection. Further, the fabricated detector based on Bi‐poor Cs2AgBiBr6 SC shows response to 59.5 keV gamma‐ray with an energy resolution of 13.91%.}, number={8}, journal={ADVANCED OPTICAL MATERIALS}, publisher={Wiley}, author={Zhang, Zheng and Cao, Da and Huang, Zhengjie and Danilov, Evgeny O. and Chung, Ching-Chang and Sun, Dali and Yang, Ge}, year={2021}, month={Apr} }
 @article{huang_vardeny_wang_ahmad_chanana_vetter_yang_liu_galli_amassian_et al._2021, title={Observation of spatially resolved Rashba states on the surface of CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> single crystals}, volume={8}, ISSN={1931-9401}, url={http://dx.doi.org/10.1063/5.0053884}, DOI={10.1063/5.0053884}, abstractNote={Hybrid organic-inorganic perovskites (HOIPs) are prime candidates for studying Rashba effects due to the heavy metal and halogen atoms in their crystal structure coupled with predicted inversion symmetry breaking. Nevertheless, observation of the Rashba effect in cubic CH3NH3PbBr3 single crystals that possess bulk inversion symmetry is the subject of extensive debate due to the lack of conclusive experiments and theoretical explanations. Here, we provide experimental evidence that Rashba state in cubic CH3NH3PbBr3 single crystals at room temperature occurs exclusively on the crystal surface and depends on specific surface termination that results in local symmetry breaking. We demonstrate this using a suite of spatially resolved and depth-sensitive techniques, including circular photogalvanic effect, inverse spin Hall effect, and multiphoton microscopy, that are supported by first principle calculations. Our work suggests using surface Rashba states in these materials for spintronic applications.}, number={3}, journal={Applied Physics Reviews}, publisher={AIP Publishing}, author={Huang, Zhengjie and Vardeny, Shai R. and Wang, Tonghui and Ahmad, Zeeshan and Chanana, Ashish and Vetter, Eric and Yang, Shijia and Liu, Xiaojie and Galli, Giulia and Amassian, Aram and et al.}, year={2021}, month={Sep}, pages={031408} }
 @article{li_yang_sun_sun_li_vetter_sun_li_yang_su_et al._2020, title={Large spin to charge conversion in the topological superconductor β−PdBi2 at room temperature}, url={https://doi.org/10.1103/PhysRevB.102.014420}, DOI={10.1103/PhysRevB.102.014420}, abstractNote={\b{eta}-PdBi2 has attracted much attention for its prospective ability to possess simultaneously topological surface and superconducting states due to its unprecedented spin-orbit interaction (SOC). Whereas most works have focused solely on investigating its topological surface states, the coupling between spin and charge degrees of freedom in this class of quantum material remains unexplored. Here we first report a study of spin-to-charge conversion in a \b{eta}-PdBi2 ultrathin film grown by molecular beam epitaxy, utilizing a spin pumping technique to perform inverse spin Hall effect measurements. We find that the room temperature spin Hall angle of Fe/\b{eta}-PdBi2, {\theta}_SH=0.037. This value is one order of magnitude larger than that of reported conventional superconductors, and is comparable to that of the best SOC metals and topological insulators. Our results provide an avenue for developing superconductor-based spintronic applications.}, journal={Physical Review B}, author={Li, Yang and Yang, Shi-jia and Sun, Dali and Sun, Yun-bin and Li, Yan and Vetter, Eric and Sun, Rui and Li, Na and Yang, Xu and Su, Lei and et al.}, year={2020}, month={Jul} }
 @article{huang_bloom_ni_georgieva_marciesky_vetter_liu_waldeck_sun_2020, title={Magneto-Optical Detection of Photoinduced Magnetism via Chirality-Induced Spin Selectivity in 2D Chiral Hybrid Organic–Inorganic Perovskites}, volume={14}, url={https://doi.org/10.1021/acsnano.0c04017}, DOI={10.1021/acsnano.0c04017}, abstractNote={The recent convergence of chiral molecules with metal halide perovskite frameworks gives rise to an interesting family of chiral systems: two-dimensional, chiral hybrid organic-inorganic perovskites (chiral-HOIPs). While possessing photovoltaic properties of traditional HOIPs, this class of materials is endowed with chirality through its organic ligands in which the degeneracy of the electron spin in charge transport is broken, i.e., the Chirality-Induced Spin Selectivity (CISS) effect manifests, making it a promising platform to bridge opto-spintronic studies and the CISS effect. In this work chiral-HOIP/NiFe heterostructures are studied by means of the magneto-optical Kerr effect using a Sagnac interferometer. Upon illumination of the chiral-HOIPs, the Kerr signal at the chiral-HOIP / NiFe interface changes and a linear dependence of the response on the magnetic field is observed. The sign of the slope was found to depend on the chirality of the HOIPs. The results demonstrate the utility of chiral-HOIP materials for chiral opto-spintronic applications.}, number={8}, journal={ACS Nano}, publisher={American Chemical Society (ACS)}, author={Huang, Zhengjie and Bloom, Brian P. and Ni, Xiaojuan and Georgieva, Zheni N. and Marciesky, Melissa and Vetter, Eric and Liu, Feng and Waldeck, David H. and Sun, Dali}, year={2020}, month={Aug}, pages={10370–10375} }
 @article{vetter_biliroglu_seyitliyev_reddy_kirste_sitar_collazo_gundogdu_sun_2020, title={Observation of carrier concentration dependent spintronic terahertz emission from n-GaN/NiFe heterostructures}, url={https://doi.org/10.1063/5.0011009}, DOI={10.1063/5.0011009}, abstractNote={The development of terahertz (THz) spintronics has created a paradigm shift in the generation of THz radiation through the combination of ultrafast magnetism and spin-based electronics. However, research in this area has primarily focused on all-metallic devices comprising a ferromagnetic thin film adjacent to a non-magnetic heavy metal. Here, we report the experimental observation of spintronic THz emission from an n-doped wide bandgap semiconductor, n-GaN. We found that the amplitude of THz emission strongly depends on the carrier concentration of the semiconductor layer, which could be attributed to the tunable Rashba state occurring at the n-GaN/ferromagnet interface. Our work offers exciting prospects for pursuing wide bandgap semiconductor-based spintronic THz devices and demonstrating their intriguing spin Hall physics at the ultrafast timescale.}, journal={Applied Physics Letters}, author={Vetter, Eric and Biliroglu, Melike and Seyitliyev, Dovletgeldi and Reddy, Pramod and Kirste, Ronny and Sitar, Zlatko and Collazo, Ramón and Gundogdu, Kenan and Sun, Dali}, year={2020}, month={Aug} }
 @article{yang_vetter_wang_amassian_sun_2020, title={Observation of long spin lifetime in MAPbBr3 single crystals at room temperature}, volume={3}, url={https://doi.org/10.1088/2515-7639/ab69b0}, DOI={10.1088/2515-7639/ab69b0}, abstractNote={Abstract}, number={1}, journal={Journal of Physics: Materials}, publisher={IOP Publishing}, author={Yang, Shijia and Vetter, Eric and Wang, Tonghui and Amassian, Aram and Sun, Dali}, year={2020}, month={Jan}, pages={015012} }
 @article{zhang_chung_huang_vetter_seyitliyev_sun_gundogdu_castellano_danilov_yang_2020, title={Towards radiation detection using Cs2AgBiBr6 double perovskite single crystals}, volume={269}, ISSN={0167-577X}, url={http://dx.doi.org/10.1016/j.matlet.2020.127667}, DOI={10.1016/j.matlet.2020.127667}, abstractNote={In this work, we studied the optical- and electrical- properties of emerging Cs2AgBiBr6 double perovskite single crystals and demonstrated their potential for detecting ionizing radiation. We prepared Cs2AgBiBr6 double perovskite single crystals from a saturated aqueous solution. Low-temperature photoluminescence (PL) was employed to determine the bandgap energies of Cs2AgBiBr6, which are 2.00 eV (indirect) and 2.26 eV (direct) respectively. Using the space charge limited current method, we estimated the density of trap states and mobility of charge carriers as 1.44 × 1010 cm−3 and 7.02 cm2/V-s respectively. A lower bound value of the mobility-lifetime (μ-τ) product of 2.48 × 10−3 cm2/V was determined using 450 nm laser excitation, which was sufficient for ensuring a long drift distance of charge carriers for several radiation detector applications. Furthermore, we tested the direct response of Cs2AgBiBr6 single crystals to X-ray radiation. Our Cs2AgBiBr6 single crystal device with gold electrodes deposited on the two parallel surfaces exhibited excellent linear response to low energy X-rays.}, journal={Materials Letters}, publisher={Elsevier BV}, author={Zhang, Zheng and Chung, Ching-Chang and Huang, Zhengjie and Vetter, Eric and Seyitliyev, Dovletgeldi and Sun, Dali and Gundogdu, Kenan and Castellano, Felix N. and Danilov, Evgeny O. and Yang, Ge}, year={2020}, month={Jun}, pages={127667} }
 @article{vetter_vonwald_yang_yan_koohfar_kumah_yu_you_sun_2020, title={Tuning of spin-orbit coupling in metal-free conjugated polymers by structural conformation}, url={https://doi.org/10.1103/PhysRevMaterials.4.085603}, DOI={10.1103/PhysRevMaterials.4.085603}, abstractNote={Manipulating spin-orbit coupling (SOC) is a key achievement for spin-orbitronic applications since SOC determines spin-diffusion lengths and spin-to-charge conversion efficiencies. While in most organic semiconductors SOC is inherently very weak due to being composed of primarily light elements, the SOC in conjugated polymer systems is also intimately tied to the polymer's structural conformation and thus may be manipulated. Here we report a modification of SOC in conjugated polymers by altering torsion angle between conjugated units. Spin-pumping experiments are performed on three poly(3-alkylthiophene) polymer films with decreasing conjugation lengths and concomitantly increasing torsion angle. The more twisted polymer exhibits a shorter spin-diffusion length and a giant spin-mixing conductance (up to ${10}^{21}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$ ), which is attributed to an increased SOC by structural conformation. This work offers a route for enhancing SOC and spin-injection efficiency in organic materials for spintronic applications.}, journal={Physical Review Materials}, author={Vetter, Eric and VonWald, Ian and Yang, Shijia and Yan, Liang and Koohfar, Sanaz and Kumah, Divine and Yu, Zhi-Gang and You, Wei and Sun, Dali}, year={2020}, month={Aug} }
 @article{fang_wang_wang_hou_vetter_kou_yang_yin_xiao_li_et al._2020, title={Tuning the interfacial spin-orbit coupling with ferroelectricity}, volume={11}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-020-16401-7}, abstractNote={Abstract}, number={1}, journal={NATURE COMMUNICATIONS}, author={Fang, Mei and Wang, Yanmei and Wang, Hui and Hou, Yusheng and Vetter, Eric and Kou, Yunfang and Yang, Wenting and Yin, Lifeng and Xiao, Zhu and Li, Zhou and et al.}, year={2020}, month={May} }
 @article{sun_yang_yang_kumar_vetter_xue_li_li_li_zhang_et al._2020, title={Visualizing Tailored Spin Phenomena in a Reduced-Dimensional Topological Superlattice}, volume={32}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202005315}, abstractNote={Emergent topological insulators (TIs) and their design are in high demand for manipulating and transmitting spin information toward ultralow‐power‐consumption spintronic applications. Here, distinct topological states with tailored spin properties can be achieved in a single reduced‐dimensional TI‐superlattice, (Bi2/Bi2Se3)‐(Bi2/Bi2Se3)N or (□/Bi2Se3)‐(Bi2/Bi2Se3)N (N is the repeating unit, □ represents an empty layer) by controlling the termination via molecular beam epitaxy. The Bi2‐terminated superlattice exhibits a single Dirac cone with a spin momentum splitting ≈0.5 Å−1, producing a pronounced inverse Edelstein effect with a coherence length up to 1.26 nm. In contrast, the Bi2Se3‐terminated superlattice is identified as a dual TI protected by coexisting time reversal and mirror symmetries, showing an unexpectedly long spin lifetime up to 1 ns. The work elucidates the key role of dimensionality and dual topological phases in selecting desired spin properties, suggesting a promise route for engineering topological superlattices for high‐performance TI‐spintronic devices.}, number={49}, journal={ADVANCED MATERIALS}, author={Sun, Rui and Yang, Shijia and Yang, Xu and Kumar, A. and Vetter, Eric and Xue, Wenhua and Li, Yan and Li, Na and Li, Yang and Zhang, Shihao and et al.}, year={2020}, month={Dec} }
 @article{yang_shi_miao_li_cai_liu_lin_bai_zhu_yu_et al._2019, title={Achieving large and nonvolatile tunable magnetoresistance in organic spin valves using electronic phase separated manganites}, volume={10}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-019-11827-0}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Yang, Wenting and Shi, Qian and Miao, Tian and Li, Qiang and Cai, Peng and Liu, Hao and Lin, Hanxuan and Bai, Yu and Zhu, Yinyan and Yu, Yang and et al.}, year={2019}, month={Aug} }
 @article{li_li_liu_xie_vetter_yuan_he_liu_sun_xia_et al._2019, title={Isotropic non-local Gilbert damping driven by spin pumping in epitaxial Pd/Fe films on MgO(001) substrates}, volume={21}, ISSN={["1367-2630"]}, url={https://doi.org/10.1088/1367-2630/ab4c8d}, DOI={10.1088/1367-2630/ab4c8d}, abstractNote={Abstract}, number={10}, journal={NEW JOURNAL OF PHYSICS}, publisher={IOP Publishing}, author={Li, Y. and Li, Y. and Liu, Q. and Xie, Z. K. and Vetter, E. and Yuan, Z. and He, W. and Liu, H. L. and Sun, D. L. and Xia, K. and et al.}, year={2019}, month={Oct} }
 @article{sun_yang_yang_vetter_sun_li_su_li_li_gong_et al._2019, title={Large Tunable Spin-to-Charge Conversion Induced by Hybrid Rashba and Dirac Surface States in Topological Insulator Heterostructures}, volume={19}, ISSN={["1530-6992"]}, DOI={10.1021/acs.nanolett.9b01151}, abstractNote={Topological insulators (TIs) have emerged as some of the most efficient spin-to-charge convertors because of their correlated spin-momentum locking at helical Dirac surface states. While endeavors have been made to pursue large "charge-to-spin" conversions in novel TI materials using spin-torque-transfer geometries, the reciprocal process "spin-to-charge" conversion, characterized by the inverse Edelstein effect length (λIEE) in the prototypical TI material (Bi2Se3), remains moderate. Here, we demonstrate that, by incorporating a "second" spin-splitting band, namely, a Rashba interface formed by inserting a bismuth interlayer between the ferromagnet and the Bi2Se3 (i.e., ferromagnet/Bi/Bi2Se3 heterostructure), λIEE shows a pronounced increase (up to 280 pm) compared with that in pure TIs. We found that λIEE alters as a function of bismuth interlayer thickness, suggesting a new degree of freedom to manipulate λIEE by engineering the interplay of Rashba and Dirac surface states. Our finding launches a new route for designing TI- and Rashba-type quantum materials for next-generation spintronic applications.}, number={7}, journal={NANO LETTERS}, author={Sun, Rui and Yang, Shijia and Yang, Xu and Vetter, Eric and Sun, Dali and Li, Na and Su, Lei and Li, Yan and Li, Yang and Gong, Zi-zhao and et al.}, year={2019}, month={Jul}, pages={4420–4426} }
 @article{hany_yang_zhou_sun_gundogdu_seyitliyev_danilov_castellano_sun_vetter_et al._2019, title={Low temperature cathodoluminescence study of Fe-doped β-Ga2O3}, volume={257}, ISSN={0167-577X}, url={http://dx.doi.org/10.1016/j.matlet.2019.126744}, DOI={10.1016/j.matlet.2019.126744}, abstractNote={Optical and electrical properties along the b-axis of Fe-doped β-Ga2O3 were studied using low temperature cathodoluminescence (CL) spectroscopy, optical absorption spectroscopy and current-voltage (IV) measurements. The optical absorption spectroscopy showed an absorption edge without near edge shoulder and the corresponding optical bandgap was calculated to be 4.45 eV using direct band gap treatment. The temperature dependent CL measurements exhibited a strong blue to ultraviolet (UV) band composed of multiple low intensity peaks in the blue range, a main blue peak, a main UV peak, and a weak UV band from the as-grown Fe-doped β-Ga2O3. After a controlled annealing in air, the emissions changed to a red to near infrared (R-NIR) band with two sharp peaks and an UV band that is resolved at room temperature to three UV broad peaks. The R-NIR sharp peaks from the air-annealed sample were ascribed to incorporation of nitrogen during air annealing.}, journal={Materials Letters}, publisher={Elsevier BV}, author={Hany, Ibrahim and Yang, Ge and Zhou, Chuanzhen Elaine and Sun, Cheng and Gundogdu, Kenan and Seyitliyev, Dovletgeldi and Danilov, Evgeny O. and Castellano, Felix N. and Sun, Dali and Vetter, Eric and et al.}, year={2019}, month={Dec}, pages={126744} }
 @article{fang_zhang_zhang_jiang_vetter_lee_xu_sun_shen_2019, title={Nonvolatile Multilevel States in Multiferroic Tunnel Junctions}, volume={12}, ISSN={["2331-7019"]}, DOI={10.1103/PhysRevApplied.12.044049}, abstractNote={Manipulation of tunneling spin-polarized electrons via a ferroelectric interlayer sandwiched between two ferromagnetic electrodes, dubbed Multiferroic Tunnel Junctions (MFTJs), can be achieved not only by the magnetic alignments of two ferromagnets but also by the electric polarization of the ferroelectric interlayer, providing great opportunities for next-generation multi-state memory devices. Here we show that a La0.67Sr0.33MnO3 (LSMO)/PbZr0.2Ti0.8O3(PZT)/Co structured MFTJ device can exhibit multilevel resistance states in the presence of gradually reversed ferroelectric domains via tunneling electro-resistance and tunneling magnetoresistance, respectively. The nonvolatile ferroelectric control in the MFTJ can be attributed to separate contributions arising from two independent ferroelectric channels in the PZT interlayer with opposite polarization. Our study shows the dominant role of "mixed" ferroelectric states on achieving accumulative electrical modulation of multilevel resistance states in MFTJs, paving the way for multifunctional device applications.}, number={4}, journal={PHYSICAL REVIEW APPLIED}, author={Fang, Mei and Zhang, Sangjian and Zhang, Wenchao and Jiang, Lu and Vetter, Eric and Lee, Ho Nyung and Xu, Xiaoshan and Sun, Dali and Shen, Jian}, year={2019}, month={Oct} }
 @article{liu_sun_zhang_groesbeck_mclaughlin_vardeny_2019, title={Observation of exceptional points in magnonic parity-time symmetry devices}, volume={5}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.aax9144}, DOI={10.1126/sciadv.aax9144}, abstractNote={Parity-time symmetry has been theoretically and experimentally demonstrated in magnonics.}, number={11}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Liu, Haoliang and Sun, Dali and Zhang, Chuang and Groesbeck, Matthew and Mclaughlin, Ryan and Vardeny, Z. Valy}, year={2019}, month={Nov} }
 @article{mclaughlin_sun_zhang_groesbeck_vardeny_2019, title={Reply to "Comment on 'Optical detection of transverse spin-Seebeck effect in permalloy film using Sagnac interferometer microscopy'"}, volume={99}, ISSN={["2469-9969"]}, DOI={10.1103/PhysRevB.99.106402}, abstractNote={In their Comment, Kimling and Kuschel (hereafter the commenters) challenge our original interpretation of the magneto-optical Kerr effect (MOKE) measurements using ultrasensitive Sagnac interferometer, claiming that the transverse spin-Seebeck effect (TSSE) is not the only contribution to the measured change in the Kerr rotation angle from a Ni80Fe20 (NiFe) ferromagnetic (FM) slab subjected to a lateral temperature gradient in the presence of a magnetic field. The authors assert that: (1) the TSSE, in general, has not been completely proven so far, and that the existing theories, in particular the phonon magnon drag model that we have used in our publication, in fact cannot explain the original work of Uchida et al. (2) The commenters based their critique on an estimate of the magnitude of the measured effect, arguing that to observe the TSSE that we originally claimed, the temperature gradient in our measurements should have been much larger than the value we measured. In this Reply, firstly, we summarize previous literature reports on the TSSE response in FM metallic systems. Secondly, we dispute the estimate of the necessary large temperature gradient made by the commenters. Importantly, the Kerr effect sensitivity to spin accumulation (via the TSSE response) has not been recognized by the commenters, in fact it was mistakenly assumed that the Kerr effect sensitivity to the spin accumulation by the TSSE is the same as the Kerr sensitivity to the bulk magnetization change due to the temperature change. In conclusion, we show that the TSSE is the only viable interpretation of our original measurements, and that the phonon-magnon drag model is indeed capable of explaining our results.}, number={10}, journal={PHYSICAL REVIEW B}, author={McLaughlin, R. and Sun, D. and Zhang, C. and Groesbeck, M. and Vardeny, Z. Valy}, year={2019}, month={Mar} }
 @article{wang_zhang_liu_mclaughlin_zhai_vardeny_liu_mcgill_semenov_guo_et al._2019, title={Spin-optoelectronic devices based on hybrid organic-inorganic trihalide perovskites}, volume={10}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-018-07952-x}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Wang, Jingying and Zhang, Chuang and Liu, Haoliang and McLaughlin, Ryan and Zhai, Yaxin and Vardeny, Shai R. and Liu, Xiaojie and McGill, Stephen and Semenov, Dmitry and Guo, Hangwen and et al.}, year={2019}, month={Jan} }
 @article{sun_zhang_kavand_wang_malissa_liu_popli_singh_vardeny_zhang_et al._2019, title={Surface-enhanced spin current to charge current conversion efficiency in CH3NH3PbBr3-based devices}, url={https://doi.org/10.1063/1.5125230}, DOI={10.1063/1.5125230}, abstractNote={Hybrid organic-inorganic perovskites have shown great promise for spintronic applications due to their large spin-orbit coupling induced by the Pb and halogen atoms. Particularly, the large observed surface-induced Rashba splitting in CH3NH3PbBr3 indicates efficient spin-current-to-charge-current (StC) conversion, which, however, has not been demonstrated yet. In this work, the StC conversion efficiency in ferromagnet/CH3NH3PbBr3-based devices is studied using the pulsed spin-pumping technique measured by the inverse spin Hall effect. We found that the StC conversion efficiency is anomalous in that it increases at small perovskite layer thickness. This indicates the existence of a surface-dominated StC mechanism such as the inverse Rashba-Edelstein effect. By inserting a thin LiF layer between the ferromagnet and the perovskite film, the StC conversion efficiency is greatly suppressed, validating the existence of a Rashba surface in the CH3NH3PbBr3 film.}, journal={The Journal of Chemical Physics}, author={Sun, Dali and Zhang, Chuang and Kavand, Marzieh and Wang, Jingying and Malissa, Hans and Liu, Haoliang and Popli, Henna and Singh, Jaspal and Vardeny, Shai R. and Zhang, Wei and et al.}, year={2019}, month={Nov} }
 @article{wang_zhang_liu_liu_guo_sun_vardeny_2019, title={Tunable Spin Characteristic Properties in Spin Valve Devices Based on Hybrid Organic-Inorganic Perovskites}, volume={31}, ISSN={["1521-4095"]}, DOI={10.1002/adma.201904059}, abstractNote={Abstract}, number={41}, journal={ADVANCED MATERIALS}, author={Wang, Jingying and Zhang, Chuang and Liu, Haoliang and Liu, Xiaojie and Guo, Hangwen and Sun, Dali and Vardeny, Zeev Valy}, year={2019}, month={Oct} }
 @article{zhang_sun_yu_sheng_mcgill_semenov_vardeny_2018, title={Field-induced spin splitting and anomalous photoluminescence circular polarization in CH3NH3PbI3 films at high magnetic field}, volume={97}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.97.134412}, abstractNote={The organic-inorganic hybrid perovskites show excellent optical and electrical properties for photovoltaic and a myriad of other optoelectronics applications. Using high-field magneto-optical measurements up to 17.5 T at cryogenic temperatures, we have studied the spin-dependent optical transitions in the prototype $\mathrm{C}{\mathrm{H}}_{3}\mathrm{N}{\mathrm{H}}_{3}\mathrm{Pb}{\mathrm{I}}_{3}$, which are manifested in the field-induced circularly polarized photoluminescence emission. The energy splitting between left and right circularly polarized emission bands is measured to be \ensuremath{\sim}1.5 meV at 17.5 T, from which we obtained an exciton effective $g$ factor of \ensuremath{\sim}1.32. Also from the photoluminescence diamagnetic shift we estimate the exciton binding energy to be \ensuremath{\sim}17 meV at low temperature. Surprisingly, the corresponding field-induced circular polarization is ``anomalous'' in that the photoluminescence emission of the higher split energy band is stronger than that of the lower split band. This ``reversed'' intensity ratio originates from the combination of long electron spin relaxation time and hole negative $g$ factor in $\mathrm{C}{\mathrm{H}}_{3}\mathrm{N}{\mathrm{H}}_{3}\mathrm{Pb}{\mathrm{I}}_{3}$, which are in agreement with a model based on the k\ifmmode\cdot\else\textperiodcentered\fi{}p effective-mass approximation.}, number={13}, journal={PHYSICAL REVIEW B}, author={Zhang, Chuang and Sun, Dali and Yu, Zhi-Gang and Sheng, Chuan-Xiang and McGill, Stephen and Semenov, Dmitry and Vardeny, Zeev Valy}, year={2018}, month={Apr} }
 @article{liu_mclaughlin_sun_vardeny_2018, title={Long-range transverse spin Seebeck effect in permalloy stripes using Sagnac interferometer microscopy}, volume={51}, ISSN={["1361-6463"]}, url={https://doi.org/10.1088/1361-6463/aab0c3}, DOI={10.1088/1361-6463/aab0c3}, abstractNote={Coupling of spins and phonons in ferromagnets (FM) may persist up to mm length scale, thus generating macroscopic spatially distributed spin accumulation along the direction of an applied thermal gradient to an FM slab. This typical feature of transverse spin Seebeck effect (TSSE) has been demonstrated so far using electrical detection methods in FM films, in particular in a patterned structure, in which FM stripes grown onto a substrate perpendicular to the applied thermal gradient direction are electrically and magnetically isolated. Here we report optically detected TSSE response in isolated FM stripes based on permalloy deposited on SiN substrate, upon the application of a thermal gradient. For these measurements we used the magneto-optic Kerr effect measured by an ultrasensitive Sagnac interferometer microscope that is immune to thermo-electrics artefacts. We found that the optical TSSE coefficient in the NiFe stripes geometry is about one order of magnitude smaller than that in the continuous NiFe film, which is due to the limited phonons path in the FM stripes along the thermal gradient direction. Our results further confirm the existence of TSSE response in conducting FM compounds.}, number={13}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, publisher={IOP Publishing}, author={Liu, Haoliang and McLaughlin, Ryan and Sun, Dali and Vardeny, Z. Valy}, year={2018}, month={Apr} }
 @article{liu_zhang_malissa_groesbeck_kavand_mclaughlin_jamali_hao_sun_davidson_et al._2018, title={Organic-based magnon spintronics}, volume={17}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/S41563-018-0035-3}, DOI={10.1038/S41563-018-0035-3}, abstractNote={Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics  1  . Magnons in inorganic materials have been studied widely with respect to their generation 2,3 , transport 4,5  and detection  6  . In contrast, resonant spin waves in the room-temperature organic-based ferrimagnet vanadium tetracyanoethylene (V(TCNE)  x  (x ≈ 2)), were detected only recently  7  . Herein we report room-temperature coherent magnon generation, transport and detection in films and devices based on V(TCNE)  x  using three different techniques, which include broadband ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and spin pumping into a Pt adjacent layer. V(TCNE)  x  can be grown as neat films on a large variety of substrates, and it exhibits extremely low Gilbert damping comparable to that in yttrium iron garnet. Our studies establish an alternative use for organic-based magnets, which, because of their synthetic versatility, may substantially enrich the field of magnon spintronics.}, number={4}, journal={Nature Materials}, publisher={Springer Science and Business Media LLC}, author={Liu, Haoliang and Zhang, Chuang and Malissa, Hans and Groesbeck, Matthew and Kavand, Marzieh and McLaughlin, Ryan and Jamali, Shirin and Hao, Jingjun and Sun, Dali and Davidson, Royce A. and et al.}, year={2018}, month={Mar}, pages={308–312} }
 @article{sun_zhai_schooten_zhang_kavand_malissa_groesbeck_menon_boehme_vardeny_2018, title={Sign reversal of magnetoresistance and inverse spin Hall effect in doped conducting polymers}, volume={30}, ISSN={["1361-648X"]}, url={https://doi.org/10.1088/1361-648X/aae86f}, DOI={10.1088/1361-648X/aae86f}, abstractNote={Conducting polymers, where pristine polymers are doped by active dopants, have been used in a variety of flexible optoelectronic device applications due to their tunable conductivity values. Charge transport in these materials has been intensively studied for over three decades. However, spin transport properties in these compounds have remained elusive. Here, we studied two polaron-dominated and trap-dominated spin transport processes in two types of PEDOT:PSS polymers that are lightly and heavily doped, respectively. Using pulsed spin-pumping and spin-injection techniques, we found the sign of inverse spin Hall effect and magnetoresistance obtained from the lightly doped PEDOT:PSS film can reverse its polarity as a function of temperature and applied bias, in contrast to that in the heavily doped PEDOT:PSS film. Our work provides an alternative approach for studying the spin transport in conducting polymer films.}, number={48}, journal={JOURNAL OF PHYSICS-CONDENSED MATTER}, publisher={IOP Publishing}, author={Sun, Dali and Zhai, Yaxin and Schooten, Kipp J. and Zhang, Chuang and Kavand, Marzieh and Malissa, Hans and Groesbeck, Matthew and Menon, Reghu and Boehme, Christoph and Vardeny, Z. Valy}, year={2018}, month={Dec} }
 @article{zhang_sun_mclaughlin_semenov_mcgill_yu_ehrenfreund_vardeny_2018, title={Triplet exciton fine structure in Pt-rich polymers studied by circularly polarized emission under high magnetic field}, volume={98}, ISSN={["2469-9969"]}, DOI={10.1103/PhysRevB.98.155205}, abstractNote={Incorporating heavy atoms into polymer chains represents an effective way to generate emissive triplets. Here we used magneto-optical emission spectroscopy up to 17.5 Tesla for studying the fine structure of the triplet exciton in a series of Pt-rich \ensuremath{\pi}-conjugated polymers with various intrachain Pt concentrations. We found that their phosphorescence emission band shows substantial field-induced circular polarization (FICPO) up to 50% with an unusual, nonmonotonic field dependence at cryogenic temperature. From the field-induced energy splitting between left and right circularly polarized phosphorescence we obtained the effective $g$ factor of triplet exciton varying in the range of $\ensuremath{-}0.13\text{\ensuremath{-}}0.85$, which depends on the Pt concentration in the polymer chains. The FICPO of triplet emission originates from the population difference in spin sublevels, which is determined by thermal equilibrium subjected to spin-orbit coupling (SOC), exchange, and Zeeman interactions. Surprisingly we also observed FICPO in the fluorescence emission that results from the singlet-triplet interaction caused by the strong SOC. From these results we extracted the various interaction parameters that describe the exciton fine structure in these Pt-contained compounds.}, number={15}, journal={PHYSICAL REVIEW B}, author={Zhang, Chuang and Sun, Dali and McLaughlin, Ryan and Semenov, Dmitry and McGill, Stephen and Yu, Zhi-Gang and Ehrenfreund, Eitan and Vardeny, Zeev Valy}, year={2018}, month={Oct} }
 @article{pang_sun_zhang_baniya_kwon_vardeny_2017, title={Manipulation of Emission Colors Based on Intrinsic and Extrinsic Magneto-Electroluminescence from Exciplex Organic Light-Emitting Diodes}, volume={4}, ISSN={["2330-4022"]}, DOI={10.1021/acsphotonics.7b00567}, abstractNote={Exciplex organic light-emitting diodes (XOLEDs) utilize nonemissive triplet excitons via a reverse intersystem crossing process of thermally activated delayed fluorescence. The small energy difference between the lowest singlet and triplet levels of exciplex also allows a magnetic field to manipulate their populations, thereby achieving ultralarge “intrinsic” magneto-electroluminescence (MEL) in XOLEDs. Here we incorporate it into a hybrid type of spintronic device (“hybrid spin-XOLED”), where the XOLED is connected to a magnetic tunnel junction with large magnetoresistance, to introduce an “extrinsic” MEL response that interferes with the “intrinsic” MEL. The ratio between two MEL contributions, the MEL value, and the field response were altered by changing the exciplex layer thickness or actively manipulated by adding another current source that drives the XOLED. Most importantly, by involving two XOLEDs (green and red) in the same circuit, the hybrid spin-XOLED shows a color change when sweeping the ma...}, number={8}, journal={ACS PHOTONICS}, author={Pang, Zhiyong and Sun, Dali and Zhang, Chuang and Baniya, Sangita and Kwon, Ohyun and Vardeny, Zeev Valy}, year={2017}, month={Aug}, pages={1899–1905} }
 @article{zhang_sun_vardeny_2017, title={Multifunctional Optoelectronic-Spintronic Device Based on Hybrid Organometal Trihalide Perovskites}, volume={3}, ISSN={2199-160X}, url={http://dx.doi.org/10.1002/AELM.201600426}, DOI={10.1002/AELM.201600426}, abstractNote={DOI: 10.1002/aelm.201600426 spin valve substantially changes its resistance (namely magnetoresistance, MR) between parallel and antiparallel magnetic configurations of its two ferromagnet electrodes, whereas the OTP device component is either of a solar cell or a LED having, respectively, photoresponsive (in photovoltaic cell) and electroluminescent (in LED). In the former device activity (Figure 1a), the OTP solar cell generates photocurrent (PC) that scales with the illumination flux, and consequently influences the magnetoconductivity response of the spin valve component, which, in turn, leads to an overall enhanced room-temperature PC up to ≈25%. This tunable magneto-PC (MPC) represents an effective way to modulate the spin valve performance with an external light source, serving as a new prototype of photon-tospin transducers (spin photodetector).[31] In the second device activity (Figure 1b), the EL emission from the OTP device component is magnetically modulated by the spin valve component resulting in a substantial increase in EL emission intensity (MEL) up to ≈85% at room temperature. In addition, we also demonstrate additional device functionality, namely, magnetic field controlled O-S LED with color-tunable EL emission.[32] The OTP devices were fabricated on patterned indium–tin oxide coated glass (15–20 Ω sq–1, Lumin. Tech.). We deposited an ≈30 nm thick hole transport layer poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS (Clevios P VP AI 4083), which was annealed in the air for 20 min at 150 °C. All the remaining processes were performed in a nitrogenfilled glove box. The MAPbI3 precursor was prepared by dissolving PbI2 (0.46 g), PbCl2 (0.83 g, Sigma Aldrich), and MAI (1.59 g, Dyenamo) in N,N-dimethylformamide (5 mL). For the MAPbBr3 OTP device, PbBr2 (0.37 g, Sigma Aldrich) and MABr (0.12 g, Dyenamo) were dissolved in dimethyl sulfoxide (2 mL). The precursor solutions were then stirred overnight on a hot plate at 50 °C. The MAPbI3 precursor was spin coated on to the PEDOT:PSS layer at 3000 rpm and annealed at 105 °C for 120 min. The MAPbBr3 layer was prepared by spin coating at 3000 rpm and by the in situ nanocrystal pinning process with chloroform,[15] followed by annealing at 90 °C for 20 min. Once cooled, a 23 mg mL–1 solution of phenyl-C61-butyric acid methyl ester (PCBM; American Dye Source) dissolved in chlorobenzene was spin coated at 1500 rpm. To elevate the EL efficiency of the MAPbBr3 device, 1,3,5-tris(1-phenyl-1H-benzimidazol -2-yl)benzene (TPBi, 50 nm) was thermally evaporated instead of PCBM as the hole blocking layer. The OTP devices were capped with an Al (100 nm) electrode that was thermally evaporated through a shadow mask. The MTJ component was fabricated using a shadow mask technique via DC magnetron and ion beam sputtering onto thermally oxidized silicon substrates. We used an MgO tunnel barrier between CoFeB and CoFe ferromagnet electrodes, where Organometal trihalide perovskites (OTPs) such as MAPbX3 (MA = CH3NH3, X = halogen) are hybrid semiconductors that are composed of organic cations within the framework of inorganic Pb–X octahedrons. Photovoltaic OTP solar cells have reached a power conversion efficiency of >20%, which is a record among solution-processed photovoltaic materials.[1–6] In addition, the OTP compounds possess unique electronic and optical properties[7–9] that make them excellent candidates for lasing[10,11] and light-emitting diodes (LEDs).[12–16] OTP photovoltaic cells have been also envisioned in other applications when combined with electrochemical cell,[17] DC motors,[18] and lithium-ion batteries,[19] achieving multiple functionalities within a single circuit. Magnetic field effects have been recently observed in OTP films and optoelectronic devices that provide opportunities to magnetically control their properties.[20] However, so far spintronic applications of OTP are still lacking because of the strong spin–orbit coupling and consequent fast spin-relaxation rate in these compounds.[21] A feasible way to overcome this disadvantage is to combine the OTP optoelectronic device with a high-performance spintronic unit, creating spintronic multifunctionalities in a “hybrid” optoelectronic–spintronic (O-S) device geometry.[22] Hysteretic control of electroluminescence (EL) and photoconductivity responses using an external magnetic field represents a marked practical application for spintronic studies. It has been realized in organic LEDs and organic solar cells by tuning the excited population of singlet and triplet excitons within the active layer.[23–25] A spin organic LED was also demonstrated by injecting spin-polarized carriers from external ferromagnet electrodes at low temperature.[26] In parallel, inorganic magnetic tunnel junctions (MTJ) show very large tunneling magnetoresistance at room temperature,[27,28] and have been recently incorporated in hybrid organic LED devices.[22] An ideal spintronic–optoelectronic device based on OTP may combine their unique material properties with the MTJ functionality to exhibit both active response to external light excitation and magnetically modulated light emission.[29] This may provide an alternative route for incorporating the OTP material family in practical spintronics applications.[30] In this work we demonstrate a “hybrid” O-S device (Figure 1), which consists of an OTP-based optoelectronic component and an inorganic spin valve component based on an MTJ. The www.advelectronicmat.de}, number={2}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Zhang, Chuang and Sun, Dali and Vardeny, Z. Valy}, year={2017}, month={Jan}, pages={1600426} }
 @article{mclaughlin_sun_zhang_groesbeck_vardeny_2017, title={Optical detection of transverse spin-Seebeck effect in permalloy film using Sagnac interferometer microscopy}, volume={95}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.95.180401}, abstractNote={Here, the authors investigate the possibility of building up nonequilibrium spin accumulation in a ferromagnetic thin film composed of a metallic alloy of nickel and iron, commonly known as permalloy. Analogously to thermoelectric generators, a temperature gradient in a ferromagnet is known to generate a distribution of accumulated electron spins over macroscopic distances, which may be used as an efficient source of spin-polarized electrons in future spintronic devices. To enable the detection and quantitative determination of this imbalance of electron spins, the authors have developed an entirely optical technique, based on the magneto-optical Kerr effect, using a Sagnac interferometer microscope with a spatial resolution of one micrometer and an absolute polarization angle resolution of ten nanoradians. This new technique is not only robust against electrical artifacts, but allows the user to measure previously inaccessible experimental geometries where the magnetization is not restricted to lying in the plane of the film.}, number={18}, journal={PHYSICAL REVIEW B}, author={McLaughlin, Ryan and Sun, Dali and Zhang, Chuang and Groesbeck, Matthew and Vardeny, Z. Valy}, year={2017}, month={May} }
 @article{odenthal_talmadge_gundlach_wang_zhang_sun_yu_valy vardeny_li_2017, title={Spin-polarized exciton quantum beating in hybrid organic–inorganic perovskites}, volume={13}, ISSN={1745-2473 1745-2481}, url={http://dx.doi.org/10.1038/NPHYS4145}, DOI={10.1038/NPHYS4145}, number={9}, journal={Nature Physics}, publisher={Springer Science and Business Media LLC}, author={Odenthal, Patrick and Talmadge, William and Gundlach, Nathan and Wang, Ruizhi and Zhang, Chuang and Sun, Dali and Yu, Zhi-Gang and Valy Vardeny, Z. and Li, Yan S.}, year={2017}, month={May}, pages={894–899} }
 @article{sun_kareis_schooten_jiang_siegel_kavand_davidson_shum_zhang_liu_et al._2017, title={Spintronic detection of interfacial magnetic switching in a paramagnetic thin film of tris(8-hydroxyquinoline)iron(III)}, volume={95}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.95.054423}, abstractNote={Dali Sun, Christopher M. Kareis , Kipp J. van Schooten, Wei Jiang, Gene Siegel, Marzieh Kavand, Royce A. Davidson, William W. Shum, Chuang Zhang, Ashutosh Tiwari, Christoph Boehme, Feng Liu, Peter W. Stephens, Joel S. Miller, Z. Valy Vardeny* Department of Physics & Astronomy, University of Utah, Salt Lake City, Utah, 84112. Department of Chemistry, University of Utah, Salt Lake City, Utah, 84112 Department of Material Science & Engineering, University of Utah, Salt Lake City, Utah 84112. Department of Physics & Astronomy, Stony Brook University, Stony Brook, NY 11794.}, number={5}, journal={PHYSICAL REVIEW B}, author={Sun, Dali and Kareis, Christopher M. and Schooten, Kipp J. and Jiang, Wei and Siegel, Gene and Kavand, Marzieh and Davidson, Royce A. and Shum, William W. and Zhang, Chuang and Liu, Haoliang and et al.}, year={2017}, month={Feb} }
 @article{zhang_sun_liu_sheng_vardeny_2017, title={Temperature-Dependent Electric Field Poling Effects in CH3NH3PbI3 Optoelectronic Devices}, volume={8}, ISSN={["1948-7185"]}, DOI={10.1021/acs.jpclett.7b00353}, abstractNote={Organo-lead halide perovskites show excellent optoelectronic properties; however, the unexpected inconsistency in forward-backward I-V characteristics remains a problem for fabricating solar panels. Here we have investigated the reasons behind this "hysteresis" by following the changes in photocurrent and photoluminescence under electric field poling in transverse CH3NH3PbI3-based devices from 300 to 10 K. We found that the hysteresis disappears at cryogenic temperatures, indicating the "freeze-out" of the ionic diffusion contribution. When the same device is cooled under continuous poling, the built-in electric field from ion accumulation brings significant photovoltaic effect even at 10 K. From the change of photoluminescence upon polling, we found a second dipole-related mechanism which enhances radiative recombination upon the alignment of the organic cations. The ionic origin of hysteresis was also verified by applying a magnetic field to affect the ion diffusion. These findings reveal the coexistence of ionic and dipole-related mechanisms for the hysteresis in hybrid perovskites.}, number={7}, journal={JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, author={Zhang, Chuang and Sun, Dali and Liu, Xiaojie and Sheng, Chuan-Xiang and Vardeny, Zeev Valy}, year={2017}, month={Apr}, pages={1429–1435} }
 @article{lafalce_zhang_zhai_sun_vardeny_2016, title={Enhanced emissive and lasing characteristics of nano-crystalline MAPbBr3 films grown via anti-solvent precipitation}, volume={120}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4964417}, DOI={10.1063/1.4964417}, abstractNote={Control of the nano-scale crystal size distribution in films of organic-inorganic lead-tri-bromide perovskites is achieved through a recently reported solution-based, anti-solvent treatment method [H. Cho et al., Science 350, 1222 (2015)]. The treated films are shown to be high quality, optically smooth with excellent emissive and optical gain properties including higher photoluminescence yield and reduced threshold for laser action. The improved lasing is shown to originate from a synergistic combination of a reduction in waveguide losses and a decrease in the non-radiative decay rate of the excited state population, compared to untreated films. The net gain is increased by a factor of two upon anti-solvent treatment and reaches a respectable value of ≈300 cm−1.}, number={14}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Lafalce, E. and Zhang, C. and Zhai, Y. and Sun, D. and Vardeny, Z. V.}, year={2016}, month={Oct}, pages={143101} }
 @article{sun_van schooten_kavand_malissa_zhang_groesbeck_boehme_valy vardeny_2016, title={Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin–orbit coupling}, volume={15}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/NMAT4618}, DOI={10.1038/NMAT4618}, abstractNote={Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temperature, and paves the way for spin orbitronics in plastic materials.}, number={8}, journal={Nature Materials}, publisher={Springer Science and Business Media LLC}, author={Sun, Dali and van Schooten, Kipp J. and Kavand, Marzieh and Malissa, Hans and Zhang, Chuang and Groesbeck, Matthew and Boehme, Christoph and Valy Vardeny, Z.}, year={2016}, month={Apr}, pages={863–869} }
 @article{baniya_pang_sun_zhai_kwon_choi_choi_lee_vardeny_2016, title={Magnetic Field Effect in Organic Light-Emitting Diodes Based on Electron Donor-Acceptor Exciplex Chromophores Doped with Fluorescent Emitters}, volume={26}, ISSN={1616-301X}, url={http://dx.doi.org/10.1002/ADFM.201601669}, DOI={10.1002/ADFM.201601669}, abstractNote={A new type of organic light‐emitting diode (OLED) has emerged that shows enhanced operational stability and large internal quantum efficiency approaching 100%, which is based on thermally activated delayed fluorescence (TADF) compounds doped with fluorescent emitters. Magneto‐electroluminescence (MEL) in such TADF‐based OLEDs and magneto‐photoluminescence (MPL) in thin films based on donor–acceptor (D–A) exciplexes doped with fluorescent emitters with various concentrations are investigated. It has been found that both MEL and MPL responses are thermally activated with substantially lower activation energy compared to that in the pristine undoped D–A exciplex host blend. In addition, both MPL and MEL steeply decrease with the emitter's concentration. This indicates the existence of a loss mechanism, whereby the triplet charge‐transfer state in the exciplex host blend may directly decay to the lowest, nonemissive triplet state of the fluorescent emitter molecules.}, number={38}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Baniya, Sangita and Pang, Zhiyong and Sun, Dali and Zhai, Yaxin and Kwon, Ohyun and Choi, Hyeonho and Choi, Byoungki and Lee, Sangyoon and Vardeny, Z. Valy}, year={2016}, month={Aug}, pages={6930–6937} }
 @article{basel_sun_baniya_mclaughlin_choi_kwon_vardeny_2016, title={Organic Light-Emitting Diodes: Magnetic Field Enhancement of Organic Light-Emitting Diodes Based on Electron Donor-Acceptor Exciplex (Adv. Electron. Mater. 2/2016)}, volume={2}, ISSN={2199-160X}, url={http://dx.doi.org/10.1002/AELM.201670012}, DOI={10.1002/AELM.201670012}, abstractNote={The electroluminescence intensity of pristine organic light emitting diodes based on donor-acceptor exciplexes is significantly enhanced upon application of an external magnetic field, as demonstrated by Basel et al. in article number 1500248. This magneto-electroluminescence causes enhancements of up to 40%, and supported by magneto-photoluminescence measurements shows the importance of reverse intersystem crossing in such systems.}, number={2}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Basel, Tek and Sun, Dali and Baniya, Sangita and McLaughlin, Ryan and Choi, Hyeonho and Kwon, Ohyun and Vardeny, Z. Valy}, year={2016}, month={Feb} }
 @article{jiang_zhou_liu_sun_vardeny_liu_2016, title={Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and their magnetic coupling with ferromagnetic surface: first-principles study}, volume={28}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/28/17/176004}, DOI={10.1088/0953-8984/28/17/176004}, abstractNote={Using first-principles calculations, we have systematically investigated the structural, electronic, and magnetic properties of facial (fac-) and meridional (mer-) tris(8-hydroxyquinoline)iron(III) (Feq3) molecules and their interaction with ferromagnetic substrate. Our calculation results show that for the isolated Feq3, mer-Feq3 is more stable than the fac-Feq3; both Feq3 isomers have a high spin-state of 5 μB as the ground state when an on-site Hubbard-U term is included to treat the highly localized Fe 3d electrons; while the standard DFT calculations produce a low spin-state of 1 μB for mer-Feq3. These magnetic behaviors can be understood by the octahedral ligand field splitting theory. Furthermore, we found that fac-Feq3 has a stronger bonding to the Co surface than mer-Feq3 and an anti-ferromagnetic coupling was discovered between Fe and Co substrate, originating from the superexchange coupling between Fe and Co mediated by the interface oxygen and nitrogen atoms. These findings suggest that Feq3 molecular films may serve as a promising spin-filter material in spintronic devices.}, number={17}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Jiang, W and Zhou, M and Liu, Z and Sun, D and Vardeny, Z V and Liu, F}, year={2016}, month={Apr}, pages={176004} }
 @article{basel_sun_baniya_mclaughlin_choi_kwon_vardeny_2015, title={Magnetic Field Enhancement of Organic Light-Emitting Diodes Based on Electron Donor-Acceptor Exciplex}, volume={2}, ISSN={2199-160X}, url={http://dx.doi.org/10.1002/AELM.201500248}, DOI={10.1002/AELM.201500248}, abstractNote={Reverse intersystem crossing (RISC) from triplet to singlet states has been recently introduced to photophysics of organic chromophores. One type of RISC occurs in donor (D)–acceptor (A) composites that form an exciplex manifold in which the energy difference, ΔEST between the lowest singlet (S1) and triplet (T1) levels of the exciplex is small (<100 meV) thus allowing RISC at room temperature. This adds a delayed component to the photoluminescence emission that is widely known as thermally activated delayed fluorescence. Here, it is found that the electroluminescence in organic light‐emitting diodes (OLED) based on electron D–A exciplex is significantly enhanced (up to ≈40%) by applying magnetic field, due to the existence of an additional spin‐mixing channel between singlet and triplet states in the exciplex. The large magneto‐electroluminescence (MEL) in N,N,N′,N′‐tetrakis(4‐methoxyphenyl)benzidine: tris‐[3‐(3‐pyridyl)mesityl]borane [D–A] based OLEDs is demonstrated. These results are supported by magneto‐photoluminescence (MPL) measurements, and density functional theory calculations. Importantly, it is found that both MEL and MPL are thermally activated indicating the dominant role of the RISC process. The MEL(B) response using the Δg mechanism is analyzed, where the electron and hole g‐values are different from each other because they reside in different molecules.}, number={2}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Basel, Tek and Sun, Dali and Baniya, Sangita and McLaughlin, Ryan and Choi, Hyeonho and Kwon, Ohyun and Vardeny, Z. Valy}, year={2015}, month={Nov}, pages={1500248} }
 @article{zhang_sun_sheng_zhai_mielczarek_zakhidov_vardeny_2015, title={Magnetic field effects in hybrid perovskite devices}, volume={11}, ISSN={1745-2473 1745-2481}, url={http://dx.doi.org/10.1038/NPHYS3277}, DOI={10.1038/NPHYS3277}, number={5}, journal={Nature Physics}, publisher={Springer Science and Business Media LLC}, author={Zhang, C. and Sun, D. and Sheng, C-X. and Zhai, Y. X. and Mielczarek, K. and Zakhidov, A. and Vardeny, Z. V.}, year={2015}, month={Mar}, pages={427–434} }
 @article{sun_fang_xu_jiang_guo_wang_yang_yin_snijders_ward_et al._2014, title={Active control of magnetoresistance of organic spin valves using ferroelectricity}, volume={5}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/NCOMMS5396}, DOI={10.1038/NCOMMS5396}, abstractNote={Organic spintronic devices have been appealing because of the long spin lifetime of the charge carriers in the organic materials and their low cost, flexibility and chemical diversity. In previous studies, the control of resistance of organic spin valves is generally achieved by the alignment of the magnetization directions of the two ferromagnetic electrodes, generating magnetoresistance. Here we employ a new knob to tune the resistance of organic spin valves by adding a thin ferroelectric interfacial layer between the ferromagnetic electrode and the organic spacer: the magnetoresistance of the spin valve depends strongly on the history of the bias voltage, which is correlated with the polarization of the ferroelectric layer; the magnetoresistance even changes sign when the electric polarization of the ferroelectric layer is reversed. These findings enable active control of resistance using both electric and magnetic fields, opening up possibility for multi-state organic spin valves.}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Sun, Dali and Fang, Mei and Xu, Xiaoshan and Jiang, Lu and Guo, Hangwen and Wang, Yanmei and Yang, Wenting and Yin, Lifeng and Snijders, Paul C. and Ward, T. Z. and et al.}, year={2014}, month={Jul} }
 @article{hukic-markosian_zhai_montanari_ott_braun_sun_vardeny_bartl_2014, title={Magnetic properties of periodically organized cobalt frameworks}, volume={116}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4883537}, DOI={10.1063/1.4883537}, abstractNote={Periodically organized magnetic cobalt frameworks have been fabricated by a combination of colloidal self-assembly and electrochemical deposition. The ordered cobalt frameworks have a closed-packed face-centered-cubic inverse opal structure and are fabricated as micrometer-thick films. The size and density of the cobalt crystallites that compose the cobalt frameworks can be modified by a thermal annealing step following the electrodeposition. Comparison of the magnetic properties (studied by magneto-optical Kerr effect (MOKE) spectroscopy) of as-deposited and annealed samples reveals strong impact of the annealing process. Fitting the obtained MOKE response to a modified Langevin model reveals optimum values of coercivity, pinning site density, and inter-domain coupling for samples that are thermally annealed at 440 °C.}, number={1}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Hukic-Markosian, Golda and Zhai, Yaxin and Montanari, Danielle E. and Ott, Steven and Braun, Adrianne and Sun, Dali and Vardeny, Zeev V. and Bartl, Michael H.}, year={2014}, month={Jul}, pages={013906} }
 @article{basel_sun_gautam_valy vardeny_2014, title={Observation of the energy transfer sequence in an organic host–guest system of a luminescent polymer and a phosphorescent molecule}, volume={155}, ISSN={0022-2313}, url={http://dx.doi.org/10.1016/J.JLUMIN.2014.06.015}, DOI={10.1016/J.JLUMIN.2014.06.015}, abstractNote={We used steady state optical spectroscopies such as photoluminescence and photoinduced absorption (PA), and magnetic-field PA (MPA) for studying the energy transfer dynamics in films and organic light emitting diodes (OLED) based on host–guest blends with different guest concentrations of the fluorescent polymer poly-[2-methoxy, 5-(2′-ethyl-hexyloxy)phenylene vinylene] (MEHPPV-host), and phosphorescent molecule PtII-tetraphenyltetrabenzoporphyrin [Pt(tpbp); guest]. We show that the energy transfer process between the excited states of the host polymer and guest molecule takes a ‘ping-pong’ type sequence, because the lowest guest triplet exciton energy, ET(guest), lies higher than that of the host, ET(host). Upon photon excitation the photogenerated singlet excitons in the host polymer chains first undergo a Förster resonant energy transfer process to the guest singlet manifold, which subsequently reaches ET(guest) by intersystem crossing. Because ET(guest)>ET(host) there is a subsequent Dexter type energy transfer from ET(guest) to ET(host). This energy transfer sequence has profound influence on the photoluminescence and electroluminescence emission spectra in both films and OLED devices based on the MEHPPV-Pt(tpbp) system.}, journal={Journal of Luminescence}, publisher={Elsevier BV}, author={Basel, Tek and Sun, Dali and Gautam, Bhoj and Valy Vardeny, Z.}, year={2014}, month={Nov}, pages={89–94} }
 @article{sun_ehrenfreund_valy vardeny_2014, title={The first decade of organic spintronics research}, volume={50}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/C3CC47126H}, DOI={10.1039/C3CC47126H}, abstractNote={The first decade of organic spintronics research has benefitted from the analogy and previous experience of the inorganic spintronics field, coupled with the unlimited versatility of organic materials synthesis. At the same time, the field of organic spintronics has developed into an attractive and promising field of its own, with rich physics and promising unique potential applications. We review here a set of significant milestones achieved in organic spintronic devices such as organic spin valves, bipolar spin-valves, and hybrid organic/inorganic light emitting diodes in comparison with representative inorganic spintronic devices. We also point out acute problems that need to be resolved before the young field of organic spintronics can mature.}, number={15}, journal={Chem. Commun.}, publisher={Royal Society of Chemistry (RSC)}, author={Sun, Dali and Ehrenfreund, Eitan and Valy Vardeny, Z.}, year={2014}, pages={1781–1793} }
 @article{guo_sun_wang_gai_kravchenko_shao_jiang_ward_snijders_yin_et al._2013, title={Growth diagram of La0.7Sr0.3MnO3 thin films using pulsed laser deposition}, volume={113}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4811187}, DOI={10.1063/1.4811187}, abstractNote={An experimental study was conducted on controlling the growth mode of La0.7Sr0.3MnO3 thin films on SrTiO3 substrates using pulsed laser deposition (PLD) by tuning growth temperature, pressure, and laser fluence. Different thin film morphology, crystallinity, and stoichiometry have been observed depending on growth parameters. To understand the microscopic origin, the adatom nucleation, step advance processes, and their relationship to film growth were theoretically analyzed and a growth diagram was constructed. Three boundaries between highly and poorly crystallized growth, 2D and 3D growth, stoichiometric and non-stoichiometric growth were identified in the growth diagram. A good fit of our experimental observation with the growth diagram was found. This case study demonstrates that a more comprehensive understanding of the growth mode in PLD is possible.}, number={23}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Guo, Hangwen and Sun, Dali and Wang, Wenbin and Gai, Zheng and Kravchenko, Ivan and Shao, Jian and Jiang, Lu and Ward, Thomas Z. and Snijders, Paul C. and Yin, Lifeng and et al.}, year={2013}, month={Jun}, pages={234301} }
 @article{sun_basel_gautam_han_jiang_parkin_valy vardeny_2013, title={Room-temperature magnetically modulated electroluminescence from hybrid organic/inorganic spintronics devices}, volume={103}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4816728}, DOI={10.1063/1.4816728}, abstractNote={We report a hybrid organic/inorganic magnetic-field controlled light-emitting diode (h-OLED), in which an inorganic magnetic tunnel junction (MTJ) with large room temperature magnetoresistance is coupled to an OLED having efficient electroluminescence. In operation, the large resistance mismatch between the MTJ and OLED components is suppressed due to the non-linear I-V characteristic of the OLED. This leads to ∼80% giant magneto-electroluminescence at room temperature with emission in the red, green, and blue spectral ranges.}, number={4}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Sun, Dali and Basel, Tek P. and Gautam, Bhoj R. and Han, Wei and Jiang, Xin and Parkin, Stuart S. P. and Valy Vardeny, Z.}, year={2013}, month={Jul}, pages={042411} }
 @article{du_he_sun_fang_liu_zhang_cheng_2010, title={Monte Carlo simulation of magnetic properties of irregular Fe islands on Pb/Si(111) substrate based on the scanning tunneling microscopy image}, volume={96}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3377814}, DOI={10.1063/1.3377814}, abstractNote={Magnetic properties of irregular Fe islands grown on Si(111) substrate with Pb buffer layer by molecular beam epitaxy have been investigated by means of Monte Carlo simulation. During the simulation, the dipolar interaction energy among islands and the demagnetization energy of each island were accurately calculated in the Fourier space with the aid of cluster multiple labeling technique. The simulated results, i.e., the magnetic hysteresis loops and the temperature dependence of remanent magnetization, are in good agreement with the experimental ones measured by in situ surface magneto-optical Kerr effect (SMOKE).}, number={13}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Du, Hai-Feng and He, Wei and Sun, Da-Li and Fang, Ya-Peng and Liu, Hao-Liang and Zhang, Xiang-Qun and Cheng, Zhao-Hua}, year={2010}, month={Mar}, pages={132502} }
 @article{du_he_liu_sun_fang_gao_zhang_cheng_2010, title={Uniaxial magnetic anisotropy of quasi-one-dimensional Fe chains on Pb/Si: A Monte Carlo simulation}, volume={108}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3494086}, DOI={10.1063/1.3494086}, abstractNote={Magnetic behaviors of Fe nanowires grown on 4° miscut Si(111) substrate with Pb buffer layers have been investigated by means of Monte Carlo method. A simple model is constructed, in which the Fe chains are assumed to be assemblies of single domain Fe nanoclusters with magnetostatic energy and exchange coupling energy. The coverage dependence of the magnetic ordering temperature TC of the system is discussed. By accurately calculating the magnetostatic energy of the Fe chains, the simulated results are in agreement with the experimental ones measured by in situ surface magneto-optical Kerr effect. In addition to the magnetostatic energy, the exchange coupling between the overlapping islands is also responsible for the ferromagnetic ordering of high coverage Fe chains at room temperature. Our model was able to predict the essential features of the system.}, number={8}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Du, Hai-Feng and He, Wei and Liu, Hao-Liang and Sun, Da-Li and Fang, Ya-Peng and Gao, Jian-Hua and Zhang, Xiang-Qun and Cheng, Zhao-Hua}, year={2010}, month={Oct}, pages={083916} }
 @article{sun_gao_zhang_zhan_he_sun_cheng_2009, title={Contribution of magnetostatic interaction to magnetization reversal of Fe3Pt nanowires arrays: A micromagnetic simulation}, volume={321}, ISSN={0304-8853}, url={http://dx.doi.org/10.1016/j.jmmm.2009.03.079}, DOI={10.1016/j.jmmm.2009.03.079}, abstractNote={Using the micromagnetic simulations, we have investigated the magnetization reversal and magnetostatic interaction of Fe3Pt nanowires arrays with wire diameters lower than 40 nm. By changing the number of interacting nanowires, N, interwire distance, a, and wire diameter, D, the effects of magnetostatic interaction on coercivity and remanence are investigated in detail. According to the simulated results, the contribution to the stray field induced by surface perpendicular magnetization at the end of wires is established.}, number={18}, journal={Journal of Magnetism and Magnetic Materials}, publisher={Elsevier BV}, author={Sun, Da-Li and Gao, Jian-Hua and Zhang, Xiang-Qun and Zhan, Qing-Feng and He, Wei and Sun, Young and Cheng, Zhao-Hua}, year={2009}, month={Sep}, pages={2737–2741} }
 @article{sun_wang_du_ning_gao_fang_zhang_sun_cheng_shen_2009, title={Uniaxial magnetic anisotropy of quasi-one-dimensional Fe chains on Pb∕Si}, volume={94}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3054340}, DOI={10.1063/1.3054340}, abstractNote={We fabricated quasi-one-dimensional Fe chains on a 4° miscut Si (111) substrate with a Pb film as a buffer layer. The magnetic properties and morphology of Fe chains were investigated by means of scanning tunneling microscope (STM) and surface magneto-optical Kerr effect (SMOKE). STM images show that Fe chains are formed by Fe random islands along the steps of the Pb film due to step decoration. SMOKE data indicate that the Fe chains exhibit in-plane uniaxial magnetic anisotropy along the step direction. The effective in-plane uniaxial anisotropy constant at room temperature was determined by means of electron spin resonance.}, number={1}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Sun, Da-Li and Wang, De-Yong and Du, Hai-Feng and Ning, Wei and Gao, Jian-Hua and Fang, Ya-Peng and Zhang, Xiang-Qun and Sun, Young and Cheng, Zhao-Hua and Shen, Jian}, year={2009}, month={Jan}, pages={012504} }
 @article{gao_sun_zhang_zhan_he_sun_cheng_2008, title={Structure and magnetic properties of the self-assembled Co52Pt48 nanowire arrays}, volume={92}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2894199}, DOI={10.1063/1.2894199}, abstractNote={Co52Pt48 nanowire arrays with diameter of about 10nm have been fabricated by electrodeposition into the anodic aluminum oxide templates. The as-deposited nanowire arrays exhibit fcc structure with [110]-preferred texture along the wire axes. The nanowire arrays present both large magnetocrystalline anisotropy along the [111] direction and strong shape anisotropy along the wire axis, resulting in high coercive fields parallel and perpendicular to the wire axes, respectively. From experimental results and micromagnetic simulation, the coercive field variation as a function of the angles evidenced that the [111] magnetocrystalline anisotropy plays important role besides shape magnetic anisotropy.}, number={10}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Gao, Jian-Hua and Sun, Da-Li and Zhang, Xiang-Qun and Zhan, Qing-Feng and He, Wei and Sun, Young and Cheng, Zhao-Hua}, year={2008}, month={Mar}, pages={102501} }
 @article{gao_zhan_he_sun_cheng_2006, title={Thermally activated magnetization reversal process of self-assembled Fe55Co45 nanowire arrays}, volume={305}, ISSN={0304-8853}, url={http://dx.doi.org/10.1016/j.jmmm.2006.01.028}, DOI={10.1016/j.jmmm.2006.01.028}, abstractNote={We have investigated the temperature dependence of the magnetic properties and the magnetic relaxation of the Fe55Co45 nanowire arrays electrodeposited into self-assembled porous alumina templates with the diameter about 10 nm. X-ray diffraction (XRD) pattern indicates that the nanowire arrays are BCC structure with [1 1 0] orientation along the nanowire axes. Owing to the strong shape anisotropy, the nanowire arrays exhibit uniaxial magnetic anisotropy with the easy magnetization direction along the nanowire axes. The coercivity at 5 K can be explained by the sphere chains of the symmetric fanning mechanism. The temperature dependence of coercivity can be interpreted by thermally activated reversal mechanism as being the localized nucleation reversal mechanism with the activation volume much smaller than the wire volume. Strong field and temperature-dependent magnetic viscosity effects were also observed.}, number={2}, journal={Journal of Magnetism and Magnetic Materials}, publisher={Elsevier BV}, author={Gao, Jian-Hua and Zhan, Qing-Feng and He, Wei and Sun, Da-Li and Cheng, Zhao-Hua}, year={2006}, month={Oct}, pages={365–371} }
 @article{gao_zhan_he_sun_cheng_2005, title={Synthesis and magnetic properties of Fe3Pt nanowire arrays fabricated by electrodeposition}, volume={86}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1944210}, DOI={10.1063/1.1944210}, abstractNote={Fe3Pt nanowire arrays were fabricated by electrodeposition of Fe2+ and Pt2+ into anodic aluminum oxide (AAO) templates. X-ray diffraction (XRD) pattern indicates that the crystallites of Fe3Pt nanowires are fcc structure with existence of strong [110] orientation along the nanowire axes. Transmission electron microscopy reveals that the diameter and length of nanowires are about 10 and 400 nm, respectively. Relatively high coercivities parallel to nanowire arrays of about 2.72 kOe at 5 K and 1.17 kOe at room temperature were achieved. The magnetic hysteresis loops demonstrate that the arrays of nanowires exhibit uniaxial magnetic anisotropy with the easy magnetization direction along the nanowire axes owing to the large shape anisotropy. The magnetization reversal process of the nanowire arrays at 5 K is discussed by symmetric fanning mechanism of sphere chains model. The temperature dependence of the coercivity parallel to nanowire arrays is interpreted by thermally activated magnetization reversal process.}, number={23}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Gao, Jian-Hua and Zhan, Qing-Feng and He, Wei and Sun, Da-Li and Cheng, Zhao-Hua}, year={2005}, month={Jun}, pages={232506} }