@article{sachan_bhaumik_pant_prater_narayan_2019, title={Diamond film growth by HFCVD on Q-carbon seeded substrate}, volume={141}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2018.09.058}, abstractNote={While hot-filament assisted chemical vapor deposition (HFCVD) is a well-established technique to synthesize diamond thin films using microdiamond seeds, the quality of grown diamond thin films is often compromised due to the presence of contaminants, i.e. graphitic entities and the eroded tungsten filament remnants, at the film-substrate interface. Here, we present a novel approach to form high-quality, contamination-free diamond thin films with HFCVD using Q-carbon precursor. The Q-carbon is a metastable phase which is formed by nanosecond laser melting of amorphous carbon and rapid quenching from the superundercooled state and consists of ∼75% sp3 and rest sp2 hybridized carbon. Using Q-carbon seeds in HFCVD, we demonstrate the growth of polycrystalline diamond film with a clean interface without any tungsten filament impurities. With large-area vibrational Raman mode analysis, we also observe a significant reduction in the presence of overall graphitic entities in the diamond film. With the realization of such a high-quality interface, we present a pathway to fabricate significantly improved diamond coatings and solid-state devices.}, journal={CARBON}, author={Sachan, Ritesh and Bhaumik, Anagh and Pant, Punam and Prater, John and Narayan, Jagdish}, year={2019}, month={Jan}, pages={182–189} }
 @article{rasic_sachan_prater_narayan_2019, title={Structure-property correlations in thermally processed epitaxial LSMO films}, volume={163}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2018.10.023}, abstractNote={Mixed-valence perovskites have drawn significant research interest in the past due to their exotic properties. Lanthanum Strontium Manganese Oxide (LSMO) shows a ferromagnetic ordering that can be tuned with the control of defects and strain. Here, experiments were performed to decouple the effects of strain and oxygen content, which together control the magnetic properties of the LSMO (La0.7Sr0.3MnO3). In this work, thermal treatments show promise in effectively controlling the ferromagnetic response of LSMO films. A set of three samples were grown on the same substrate-buffer (Al2O3/MgO) platform with different oxygen partial pressures and annealed above their deposition temperature (∼900 °C) in air. The physical and structural properties were measured and showed overall decrease in magnetization saturation as well as decrease in out-of-plane lattice spacing with decreasing oxygen partial pressure. A second anneal at lower (∼700 °C) temperature with flow of pure oxygen was performed for six hours to allow for defect annihilation and grain growth. All three films remained epitaxial allowing for direct correlation of magnetic measurements with defect concentration. Partial recovery of the magnetic properties and a slight increase in interplanar spacing was observed. The inability of the films to fully recover their original magnetic properties suggests irreversible strain relaxation during the initial, high-temperature air anneal. This hypothesis was further supported by the in-situ XRD that showed a linear increase in the interplanar spacing with temperature until ∼520 °C for LSMO and ∼690 °C for MgO. With further increase in temperature, the films experienced both loss of oxygen and irreversible defect nucleation and recombination. High resolution high-angle annular dark field (HAADF) images showed uniform thickness and no interfacial mixing with subsequent annealing treatments while electron energy loss spectroscopy (EELS) showed a loss of characteristic pre-peak A in oxygen indicating formation of oxygen vacancies. Parallel annealing experiments in high vacuum instead of atmosphere were performed, which showed complete loss of crystal structure in the LSMO films due to significant loss of oxygen in the lattice that irreversibly collapsed the perovskite structure. Furthermore, a low-temperature (∼500 °C) oxidation anneal was performed on a pristine sample with no change in the interplanar spacing observed indicating no change in the strain state of the film due to annealing below the deposition temperature. The reversibility of magnetic properties, which is observed as long as the crystal structure of the films is preserved, indicates the importance of bridging oxygen in controlling the magnetic behavior of mixed valence perovskites. Finally, it was determined that the highest magnetization saturation in the films is achieved with a high oxygen partial pressure during growth and subsequent thermal annealing below the deposition temperature.}, journal={ACTA MATERIALIA}, author={Rasic, Daniel and Sachan, Ritesh and Prater, John and Narayan, Jagdish}, year={2019}, month={Jan}, pages={189–198} }
 @article{moatti_sachan_prater_narayan_2018, title={An optimized sample preparation approach for atomic resolution in situ studies of thin films}, volume={81}, ISSN={1059-910X 1097-0029}, url={http://dx.doi.org/10.1002/JEMT.23130}, DOI={10.1002/jemt.23130}, abstractNote={Abstract}, number={11}, journal={Microscopy Research and Technique}, publisher={Wiley}, author={Moatti, Adele and Sachan, Ritesh and Prater, John and Narayan, Jagdish}, year={2018}, month={Oct}, pages={1250–1256} }
 @article{moog_singamaneni_prater_biegalski_tsui_2018, title={Magneto-optical properties of BaTiO3/La0.76Sr0.24MnO3/BaTiO3 heterostructures}, volume={8}, ISSN={["2158-3226"]}, DOI={10.1063/1.5006458}, abstractNote={The magnetic properties of epitaxial BaTiO3/La0.76Sr0.24MnO3/BaTiO3 (BTO/LSMO/BTO) heterostructures have been studied using magneto-optic Kerr effect (MOKE) technique. Both longitudinal and polar MOKE were probed as a function of magnetic field and temperature (in the range between 80 and 320 K) for epitaxial films of BTO/LSMO/BTO and LSMO grown on TiO2-terminated SrTiO3 (001) substrates by pulsed laser deposition technique. The LSMO film without the BTO layers exhibits nearly square field-dependent MOKE hysteresis loops with low saturation fields below a bulk-like Curie temperature (TC) of ∼ 350K. In contrast, the film with the BTO layers exhibits a significantly suppressed TC of 155 K, accompanied by significantly enhanced coercive fields and perpendicular magnetic anisotropy.}, number={5}, journal={AIP ADVANCES}, author={Moog, M. and Singamaneni, S. R. and Prater, J. T. and Biegalski, M. D. and Tsui, F.}, year={2018}, month={May} }
 @article{singamaneni_prater_glavic_lauter_narayan_2018, title={Polarized neutron reflectivity studies on epitaxial BiFeO3/La0.7Sr0.3MnO3 heterostructure integrated with Si (100)}, volume={8}, ISSN={2158-3226}, url={http://dx.doi.org/10.1063/1.5006473}, DOI={10.1063/1.5006473}, abstractNote={This work reports polarized neutron reflectivity (PNR) measurements performed using the Magnetism Reflectometer at Oak Ridge National Laboratory on epitaxial BiFeO3(BFO)/La0.7Sr0.3MnO3(LSMO)/SrTiO3(STO)/MgO/TiN heterostructure deposited on Si (100) substrates. By measuring the angular dependence of neutrons reflected from the sample, PNR can provide insights on interface magnetic spin structure, chemical composition and magnetic depth profiles with a nanometer resolution. Our first analysis of nuclear scattering length density (NSLD) and magnetic scattering length density (MSLD) depth profiles measured at 4 K have successfully reproduced most of the expected features of this heterostructure, such as the NSLD for the Si, TiN, MgO, STO, LSMO layers and remanent magnetization (2.28μB/Mn) of bulk LSMO. However, the SLD of the BFO is decreased by about 30% from the expected value. When 5 V was applied across the BFO/LSMO interface, we found that the magnetic moment of the LSMO layer could be varied by about 15-20% at 6 K. Several mechanisms such as redistribution of oxygen vacancies, interface strain, charge screening and valence state change at the interface could be at play. Work is in progress to gain an improved in-depth understanding of these effects using MOKE and STEM-Z interface specific measurements.}, number={5}, journal={AIP Advances}, publisher={AIP Publishing}, author={Singamaneni, S. R. and Prater, J. T. and Glavic, A. and Lauter, V. and Narayan, J.}, year={2018}, month={May}, pages={055821} }
 @article{singamaneni_prater_glavic_lauter_narayan_2018, title={Polarized neutron reflectivity studies on epitaxial BiFeO3/La0.7Sr0.3MnO3 heterostructure integrated with Si (100)}, volume={8}, number={5}, journal={AIP Advances}, author={Singamaneni, S. R. and Prater, J. T. and Glavic, A. and Lauter, V. and Narayan, J.}, year={2018} }
 @article{moatti_sachan_prater_narayan_2017, title={Control of Structural and Electrical Transitions of VO2 Thin Films}, volume={9}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.7b05620}, DOI={10.1021/acsami.7b05620}, abstractNote={Unstrained and defect-free VO2 single crystals undergo structural (from high-temperature tetragonal to low-temperature monoclinic phase) and electronic phase transitions simultaneously. In thin films, however, in the presence of unrelaxed strains and defects, structural (Peierls) and electronic (Mott) transitions are affected differently, and are separated. In this paper, we have studied the temperature dependence of structural and electrical transitions in epitaxially grown vanadium dioxide films on (0001) sapphire substrates. These results are discussed using a combined kinetics and thermodynamics approach, where the velocity of phase transformation is controlled largely by kinetics, and the formation of intermediate phases is governed by thermodynamic considerations. We have grown (020) VO2 on (0001) sapphire with two (001) and (100) in-plane orientations rotated by 122°. The (100)-oriented crystallites are fully relaxed by the paradigm of domain-matching epitaxy, whereas (001) crystallites are not relaxed and exhibit the formation of a few atomic layers of thin interfacial V2O3. We have studied the structural (Peierls) transition by temperature-dependent in situ X-ray diffraction measurements, and electronic (Mott) transition by electrical resistance measurements. A delay of 3 °C is found between the onset of structural (76 °C) and electrical (73 °C) transitions in the heating cycle. This temporal lag in the transition is attributed to the residual strain existing in the VO2 crystallites. With this study, we suggest that the control of structural and electrical transitions is possible by varying the transition activation barrier for atomic jumps through the strain engineering.}, number={28}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Moatti, Adele and Sachan, Ritesh and Prater, John and Narayan, Jay}, year={2017}, month={Jul}, pages={24298–24307} }
 @article{singamaneni_prater_narayan_2017, title={Exchange bias in Ba0.4Sr0.6TiO3/La0.7Sr0.3MnO3 heterostructures}, volume={7}, number={5}, journal={AIP Advances}, author={Singamaneni, S. R. and Prater, J. T. and Narayan, J.}, year={2017} }
 @article{foley_singamaneni_prater_narayan_2016, title={Control of Magnetic Coercivity in epitaxial Ni/VO2/YSZ/Si(001) heterostructures by manipulation of Ni thin film growth modes}, volume={1}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2016.397}, abstractNote={The control of ferromagnetic properties by external stimuli is of great interest in the electronics community. One method of producing such a control is through proximity of a ferromagnetic film with a material that has a semiconductor-to-metal transition (SMT). In order for these magnetic heterostructures to be beneficial, they must consist of high-quality, crystalline films. Epitaxial films increase the reproducibility of both devices and properties. We have investigated the trend in magnetic coercivity in epitaxial nickel films on VO_2. We show that not only does the interaction between the Ni and VO_2 change the normal coercivity trend found in Ni M-H curves with no proximity to VO_2, but that the crystalline growth mode of the Ni film also impacts the magnetic coercivity as a function of temperature.}, number={50}, journal={MRS ADVANCES}, author={Foley, Gabrielle M. and Singamaneni, Srinivasa Rao and Prater, John and Narayan, Jay}, year={2016}, pages={3409–3414} }
 @article{singamaneni_punugupati_prater_narayan_2016, title={Diamagnetism to ferromagnetism in Sr-substituted epitaxial BaTiO3 thin films}, volume={108}, number={14}, journal={Applied Physics Letters}, author={Singamaneni, S. R. and Punugupati, S. and Prater, J. T. and Narayan, J.}, year={2016} }
 @article{singamaneni_prater_narayan_2016, title={Enhanced Coercivity in BiFeO3/SrRuO3 heterostructures}, volume={1}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2016.220}, abstractNote={Transition metal oxide thin film heterostructures have garnered increasing research interest in the last decade due to their multifunctional properties, such as ferromagnetism and ferroelectricity, which may be utilized in next generation device applications. Many previous works reported on the deposition of such structures on oxide substrates such as SrTiO_3, which are not compatible with CMOS applications where Si(100) is the mainstay substrate material . BiFeO_3 (BFO) is a room temperature insulating ferroelectric and antiferromagnet, a well-known multiferroic material. SrRuO_3 (SRO) is a ferromagnetic metal with the Curie temperature (T_C) of 165K. Unexpected properties emerge when these two dissimilar materials are conjoined. However, there has been no report on exploring the magnetic properties of BFO when it is in contact with SRO, and particularly when they are integrated with Si(100) substrates, which is the subject of present study. BFO/SRO thin films have been epitaxially grown on Si (100) substrates by introducing MgO/TiN epitaxial buffer layers using pulsed laser deposition. BFO thin films show room temperature ferroelectricity as observed from piezo force microscopy (PFM) measurements. The magnetic data collected from BFO thin films show typical antiferromagnetic features as expected. The T_C of SRO in all the samples studied was found be ~ 170K, close to the reported value of 165K. Interestingly, we have noticed that the coercive field of SRO layer increased from 4 kOe to 15 kOe (nearly fourfold) by reducing its thickness from 180 to 23nm, while keeping the thickness of BFO layer constant at 100nm. Pinning of Ru ions by ferroelectric domain walls in BFO, strong interfacial exchange coupling and SRO layer thickness could cause the observed enhancement in coercivity. Our near future work will address the precise underlying mechanisms in greater detail.}, number={9}, journal={MRS ADVANCES}, author={Singamaneni, Srinivasa Rao and Prater, J. T. and Narayan, J.}, year={2016}, pages={597–602} }
 @article{singamaneni_prater_wu_narayan_2016, title={Ferromagnetic oxide heterostructures on silicon}, volume={6}, ISSN={["2159-6867"]}, DOI={10.1557/mrc.2016.22}, abstractNote={Heterostructures consisting of two ferromagnetic oxides La_0.7Ca_0.3MnO_3 (LCMO) and SrRuO_3 (SRO) were epitaxially grown by pulsed laser deposition onto a silicon (Si) substrate buffered by SrTiO_3 (STO)/MgO/TiN. The x-ray scans and electron-diffraction patterns reveal the epitaxial nature of all five layers. From transmission electron microscopy, the thicknesses of the LCMO and SRO layers were estimated to be -100 and -200 nm, respectively. The magnetic properties of individual SRO and LCMO layers are in good agreement with the previous studies reported for those individual layers deposited on lattice-matched substrates, such as STO. The LCMO/SRO heterostructures showed enhanced switching field (from 6008 to 7600 Oe), which may originate from the bulk part of the heterostructure. The ability to grow these multifunctional structures on Si provides a route for wafer scale integration with Si, in contrast to oxide substrates that are not suitable for CMOS integration for microelectronics and spintronics applications.}, number={3}, journal={MRS COMMUNICATIONS}, author={Singamaneni, Srinivasa Rao and Prater, J. T. and Wu, Fan and Narayan, J.}, year={2016}, month={Sep}, pages={234–240} }
 @article{singamaneni_prater_lee_misra_narayan_2016, title={Memristive behavior in BaTiO3/La0.7Sr0.3MnO3 heterostructures integrated with semiconductors}, volume={1}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2016.70}, abstractNote={Ferroelectric materials such as BaTiO_3 have been studied for emerging non-volatile memory applications. However, most of the previous work has been focused on this material when it was deposited on insulting oxide substrates such as SrTiO_3. Unfortunately, this substrate is not suitable for CMOS-based microelectronics applications. This motivated us to carry out the present work. We have studied the resistive switching behavior in BaTiO_3/La_0.7Sr_0.3MnO_3 (BTO/LSMO) heterostructures integrated with semiconducting substrates Si (100) using MgO/TiN buffer layers by pulsed laser deposition. Current-Voltage (I-V) measurements were conducted on BTO (500nm)/LSMO (25nm) devices at 200K. We have observed a broad hysteresis in forward and reverse voltage sweeps which is an important property for memory applications. Secondly, the R_ON/R_OFF ratio is estimated at ~ 150, consistent with the reported numbers (30-100) in the literature. Thirdly, the device is stable at least up to 50 cycles. However, we found that hysteretic behavior was suppressed upon oxygen annealing of the device at 1 atmospheric pressure, 200^o C for 1hr, inferring the important role of oxygen vacancies in the resistive switching behavior of BTO/LSMO device. Future work will focus on investigating the correlation between ferroelectricity and resistive switching in these devices using local probe technique piezo force microscopy (PFM) technique.}, number={4}, journal={MRS ADVANCES}, author={Singamaneni, Srinivasa Rao and Prater, John and Lee, Bongmook and Misra, Veena and Narayan, Jay}, year={2016}, pages={275–280} }
 @article{singamaneni_fan_prater_narayan_2015, title={Complete vertical M-H loop shift in La0.7Sr0.3MnO3/SrRuO3 thin film heterostructures}, volume={117}, number={17}, journal={Journal of Applied Physics}, author={Singamaneni, S. R. and Fan, W. and Prater, J. T. and Narayan, J.}, year={2015} }
 @article{singamaneni_prater_nori_kumar_lee_misra_narayan_2015, title={Ferroelectric and magnetic properties of multiferroic BiFeO3-La0.7Sr0.3MnO3 heterostructures integrated with Si (100)}, volume={117}, number={17}, journal={Journal of Applied Physics}, author={Singamaneni, S. R. and Prater, J. T. and Nori, S. and Kumar, D. and Lee, B. and Misra, V. and Narayan, J.}, year={2015} }
 @misc{singamaneni_prater_narayan_2015, title={Magnetic exchange coupling in bilayers of two epitaxial ferromagnetic oxides}, volume={19}, ISSN={["1879-0348"]}, DOI={10.1016/j.cossms.2015.03.002}, abstractNote={Despite a decade of research effort on La0.7Sr0.3MnO3/SrRuO3 (LSMO/SRO) bilayers (BLs), a full knowledge on the magnetic properties and integration of these BLs on silicon substrate is not yet in sight. In this paper, we report on the magnetic exchange coupling observed from the above two ferromagnetic oxide thin film BLs, prepared through a novel approach, called ‘domain matching epitaxy’. LSMO (100 nm)/SRO (45 nm) and LSMO (31 nm)/SRO (45 nm) bilayers have been epitaxially integrated with Si (1 0 0). Notably, in the former sample, positive exchange bias is observed – an indication of antiferromagnetic exchange coupling and is found to be absent in the latter. Furthermore, in the former sample, the cross-over from antiferromagnetic to ferromagnetic interface exchange coupling is noticed by varying the cooling field. We have verified that this coupling is of magnetic origin, not due to electrostatic interaction by inserting a thin (∼10 nm) SrTiO3 layer between LSMO and SRO. We believe that in addition to the formation of interface domain walls, the strong interplay among Zeeman, anisotropic and exchange energies could play a dominant role. Our results would have important implications for devices comprising of magnetic exchange coupled systems.}, number={5}, journal={CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE}, author={Singamaneni, Srinivasa Rao and Prater, John T. and Narayan, Jagdish}, year={2015}, month={Oct}, pages={301–304} }
 @misc{singamaneni_narayan_prater_2015, title={Multifunctional heterostructures integrated on Si (100)}, volume={4}, number={1}, journal={Emerging Materials Research}, author={Singamaneni, S. R. and Narayan, J. and Prater, J. T.}, year={2015}, pages={50–70} }
 @misc{rao_prater_wu_nori_kumar_narayan_2014, title={Integration of epitaxial permalloy on Si (100) through domain matching epitaxy paradigm}, volume={18}, ISSN={["1879-0348"]}, DOI={10.1016/j.cossms.2013.07.004}, abstractNote={Abstract This paper addresses epitaxial integration of magnetic materials with Si (1 0 0) based solid state devices. Epitaxial Ni82.5Fe17.5 (permalloy, Py) thin films have been synthesized by pulsed laser deposition (PLD) on Si (1 0 0) using MgO/TiN as a template buffer. This epitaxial growth of these large lattice misfit systems was achieved through domain matching epitaxy (DME). The in-plane XRD pattern and selective area electron diffraction (SAED) results clearly indicate cube-on-cube epitaxial alignment. The bright field TEM image of Py/MgO/TiN/Si (1 0 0) heterostructure infers a Py layer thickness of ∼30 nm, with a well aligned island (150–200 nm) structure that is consistent with Volmer–Weber type growth. Magnetization data collected at 4 K and 300 K indicates that the easy axis of the magnetization lies in the plane of the Py. In addition, we have observed an intrinsic positive exchange bias (PEB) field of ∼104 Oe, where the magnetic hysteresis loop is shifted toward the positive field axis under zero field cooling conditions.}, number={1}, journal={CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE}, author={Rao, S. S. and Prater, J. T. and Wu, Fan and Nori, Sudhakar and Kumar, D. and Narayan, J.}, year={2014}, month={Feb}, pages={1–5} }
 @article{rao_lee_prater_smirnov_narayan_2014, title={Laser annealing induced ferromagnetism in SrTiO3 single crystal}, volume={105}, number={4}, journal={Applied Physics Letters}, author={Rao, S. S. and Lee, Y. F. and Prater, J. T. and Smirnov, A. I. and Narayan, J.}, year={2014} }
 @article{singamaneni_fan_prater_narayan_2014, title={Magnetic properties of BaTiO3/La0.7Sr0.3MnO3 thin films integrated on Si(100)}, volume={116}, number={22}, journal={Journal of Applied Physics}, author={Singamaneni, S. R. and Fan, W. and Prater, J. T. and Narayan, J.}, year={2014} }
 @article{rao_prater_wu_nori_kumar_yue_liou_narayan_2014, title={Positive exchange bias in epitaxial permalloy/MgO integrated with Si (100)}, volume={18}, ISSN={1359-0286}, url={http://dx.doi.org/10.1016/J.COSSMS.2014.02.001}, DOI={10.1016/j.cossms.2014.02.001}, abstractNote={In magnetic random access memory (MRAM) devices, soft magnetic thin film elements such as permalloy (Py) are used as unit cells of information. The epitaxial integration of these elements with the technologically important substrate Si (1 0 0) and a thorough understanding of their magnetic properties are critical for CMOS-based magnetic devices. We report on the epitaxial growth of Ni82.5Fe17.5 (permalloy, Py) on Si (1 0 0) using a TiN/MgO buffer layer. Initial stages of growth are characterized by the formation of discrete islands that gradually merge into a continuous film as deposition times are extended. Interestingly, we find that the magnetic features of Py films in early stages of island coalescence are distinctly different from the films formed initially (discrete islands) and after extended deposition times (narrow distribution of equiaxed granular films). Isothermal in-plane and out-of-plane magnetic measurements performed on these transitional films show highly anisotropic magnetic behavior with an easy magnetization axis lying in the plane of the film. Importantly, when this sample is zero-field cooled, a positive exchange bias and vertical loop shift are observed, unusual for a soft ferromagnet like Py. Repeated field cycling and hysteresis loops up to the fields of 7T produced reproducible hysteresis loops indicating the existence of strongly pinned spin configurations. Classical interface related exchange bias models cannot explain the observed magnetic features of the transitional Py films. We believe that the anomalous magnetic behavior of such Py films may be explained by considering the highly irregular morphology that develops at intermediate growth times that are possibly also undergoing a transition from Bloch to Neel domain wall structures as a function of Py island size. This study broadens the current understanding of magnetic properties of Py thin layers for technological applications in magneto-electronic devices, integrated with Si (1 0 0).}, number={3}, journal={Current Opinion in Solid State and Materials Science}, publisher={Elsevier BV}, author={Rao, S.S. and Prater, J.T. and Wu, Fan and Nori, S. and Kumar, D. and Yue, L. and Liou, S.-H. and Narayan, J.}, year={2014}, month={Jun}, pages={140–146} }
 @misc{wu_rao_prater_zhu_narayan_2014, title={Tuning exchange bias in epitaxial Ni/MgO/TiN heterostructures integrated on Si(100)}, volume={18}, ISSN={["1879-0348"]}, DOI={10.1016/j.cossms.2014.09.002}, abstractNote={Epitaxial Ni thin films are integrated with tunneling barrier MgO on Si(1 0 0) substrate. During pulsed laser deposition, early island-like structure transformed into uniform thin film with increasing number of laser pulses. This led to transitions in exchange bias from positive to negative and back to positive, which is ascribed to morphology associated residual strain. The Ni island structure has a coercive field as high as 3 times of that of the continuous film. The current work holds a tremendous promise in the realization of magnetic devices integrated with the Si-platform.}, number={5}, journal={CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE}, author={Wu, F. and Rao, S. S. and Prater, J. T. and Zhu, Y. T. and Narayan, J.}, year={2014}, month={Oct}, pages={263–268} }
 @article{molaei_bayati_nori_kumar_prater_narayan_2013, title={Diamagnetic to ferromagnetic switching in VO2 epitaxial thin films by nanosecond excimer laser treatment}, volume={103}, number={25}, journal={Applied Physics Letters}, author={Molaei, R. and Bayati, R. and Nori, S. and Kumar, D. and Prater, J. T. and Narayan, J.}, year={2013} }
 @article{rao_prater_wu_shelton_maria_narayan_2013, title={Interface Magnetism in Epitaxial BiFeO3-La0.7Sr0.3MnO3 Heterostructures Integrated on Si(100)}, volume={13}, ISSN={["1530-6992"]}, DOI={10.1021/nl4023435}, abstractNote={We report on the heteroepitaxial growth of ferroelectric (FE)-antiferromagnetic (AFM) BiFeO3 (BFO) on ferromagnetic La0.7Sr0.3MnO3 (LSMO), integrated on Si(100) using pulsed laser deposition via the domain matching epitaxy paradigm. The BFO/LSMO films were epitaxially grown on Si(100) by introducing epitaxial layers of SrTiO3/MgO/TiN. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photo absorption spectroscopy, and atomic force microscopy were employed to fully characterize the samples. Furthermore, we have investigated the magnetic behavior of this five layer heterostructure, in which a d(5) system (Fe(3+)) manifested in FE-AFM BFO is epitaxially conjoined at the interface to a multivalent transition metal ion such as Mn(3+)/Mn(4+) in LSMO. The temperature- and magnetic field-dependent magnetization measurements reveal an unexpected enhancement in magnetic moment and improved magnetic hysteresis squareness originating from the BFO/LSMO interface. We observe a stronger temperature dependence of HEB when the polarity of field cooling is negative as compared to positive field cooling. We believe such an enhancement in magnetic moment and magnetic coupling is likely directly related to an electronic orbital reconstruction at the interface and complex interplay between orbital and spin degrees of freedom, similar to what has previously been reported in the literature. Future work will involve the linearly polarized X-ray absorption measurements to prove this hypothesis. This work represents a starting step toward the realization of magneto-electronic devices integrated with Si(100).}, number={12}, journal={NANO LETTERS}, author={Rao, S. S. and Prater, J. T. and Wu, Fan and Shelton, C. T. and Maria, J. -P. and Narayan, J.}, year={2013}, month={Dec}, pages={5814–5821} }
 @article{ma_prater_sudakar_rosenberg_narayan_2012, title={Defects in room-temperature ferromagnetic Cu-doped ZnO films probed by x-ray absorption spectroscopy}, volume={24}, number={30}, journal={Journal of Physics. Condensed Matter}, author={Ma, Q. and Prater, J. T. and Sudakar, C. and Rosenberg, R. A. and Narayan, J.}, year={2012} }
 @article{mal_yang_gupta_prater_narayan_2011, title={Thin film epitaxy and magnetic properties of STO/TiN buffered ZnO on Si(001) substrates}, volume={59}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2010.12.058}, abstractNote={Abstract We report integration of epitaxial ZnO films with Si(0 0 1) substrates using STO/TiN buffer layers. It has been demonstrated that the preferential orientation of the a-plane ( 1 1 2 ¯ 0 ) and c-plane (0 0 0 2) of ZnO can be controlled via deposition temperature and oxygen partial pressure. At lower substrate temperatures ZnO grows solely in the (0 0 0 2) orientation, while the ( 1 1 2 ¯ 0 ) orientation was dominant at high substrate temperatures and low oxygen pressures. At higher pressures, the (0 0 0 2) orientation is preferred, while ( 1 1 2 ¯ 0 ) becomes weaker and a ( 1 0 1 ¯ 2 ) ZnO appears. Epitaxial relationships have been determined from X-ray diffraction φ-scans and it was found that both c- and a-ZnO had two types of orientations due to the cubic symmetry of the STO buffer layer. The orientation relationship of c-ZnO on STO(0 0 1) was ZnO(0 0 0 1) ∥ STO(1 0 0); ZnO[ 1 1 2 ¯ 0 ] ∥ STO[1 1 0] and ZnO[ 1 ¯ 2 1 ¯ 0 ] ∥ STO[ 1 ¯ 1 0 ], while that of a-ZnO on STO(0 0 1) was ZnO( 1 1 2 ¯ 0 ) ∥ STO(1 0 0); ZnO[ 1 1 2 ¯ 0 ] ∥ STO[1 1 0] and ZnO[0 0 0 2] ∥ STO[ 1 ¯ 1 0 ]. High-resolution transmission electron microscopy studies revealed atomically sharp interfaces with no reaction at the interface. Reversible d0 ferromagnetism was found to be present in both ZnO and STO layers. Our electron-energy-loss spectroscopy studies conclusively rule out the presence of any external ferromagnetic ions or impurities. Taken together, our data indicate that the ferromagnetic order in these undoped oxides might be defect mediated.}, number={6}, journal={ACTA MATERIALIA}, author={Mal, Siddhartha and Yang, Tsung-Han and Gupta, P. and Prater, J. T. and Narayan, J.}, year={2011}, month={Apr}, pages={2526–2534} }
 @article{narayan_nori_ramachandran_prater_2009, title={The synthesis and magnetic properties of a nanostructured Ni-MgO system}, volume={61}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-009-0093-8}, number={6}, journal={JOM}, author={Narayan, J. and Nori, Sudhakar and Ramachandran, S. and Prater, J. T.}, year={2009}, month={Jun}, pages={76–81} }
 @article{ramachandran_prater_sudhakar_kumar_narayan_2008, title={Magnetic properties of epitaxial oxide heterostructures}, volume={145}, ISSN={["1879-2766"]}, DOI={10.1016/j.ssc.2007.10.005}, abstractNote={Diluted Magnetic Semiconductors (DMS) are of great interest as injection sources for spin-polarized currents into semiconductors. Epitaxial devices have been synthesized with an intermediate spacer layer of the same semiconductor (zinc oxide, ZnO) used to produce the DMS material (ZnCoO) ensuring a homoepitaxial junction to help reduce the interface states and conduction mismatch. We observe a large magnetoresistance of about 32% in the devices at low temperatures. The present work suggests that spin polarized transport could be achieved with DMS materials acting as the source of injected spins into a non-magnetic host.}, number={1-2}, journal={SOLID STATE COMMUNICATIONS}, author={Ramachandran, S. and Prater, J. T. and Sudhakar, N. and Kumar, D. and Narayan, J.}, year={2008}, month={Jan}, pages={18–22} }
 @article{trichy_chakraborti_narayan_prater_2008, title={Structure-magnetic property correlations in the epitaxial FePt system}, volume={92}, number={10}, journal={Applied Physics Letters}, author={Trichy, G. R. and Chakraborti, D. and Narayan, J. and Prater, J. T.}, year={2008} }
 @article{bhosle_prater_narayan_2007, title={Anisotropic magnetic properties in [110] oriented epitaxial La0.7Sr0.3MnO3 films on (0001) sapphire}, volume={102}, number={1}, journal={Journal of Applied Physics}, author={Bhosle, V. and Prater, J. T. and Narayan, J.}, year={2007} }
 @article{bhosle_prater_yang_burk_forrest_narayan_2007, title={Gallium-doped zinc oxide films as transparent electrodes for organic solar cell applications}, volume={102}, number={2}, journal={Journal of Applied Physics}, author={Bhosle, V. and Prater, J. T. and Yang, F. and Burk, D. and Forrest, S. R. and Narayan, J.}, year={2007} }
 @article{chakraborti_ramachandran_trichy_narayan_prater_2007, title={Magnetic, electrical, and microstructural characterization of ZnO thin films codoped with Co and Cu}, volume={101}, number={5}, journal={Journal of Applied Physics}, author={Chakraborti, D. and Ramachandran, S. and Trichy, G. and Narayan, J. and Prater, J. T.}, year={2007} }
 @article{chakraborti_trichy_prater_narayan_2007, title={The effect of oxygen annealing on ZnO : Cu and ZnO :(Cu,Al) diluted magnetic semiconductors}, volume={40}, ISSN={["1361-6463"]}, DOI={10.1088/0022-3727/40/24/002}, abstractNote={Here we report a systematic study of magnetic, electronic and microstructural properties of Cu-doped and Cu and Al codoped ZnO thin films, grown epitaxially on a (0 0 0 1) sapphire substrate by the pulsed laser deposition technique. The films were annealed in oxygen at high temperature (600 °C) and their properties were compared with the as deposited films in order to study the role of defects like oxygen vacancies on the ferromagnetic properties. The doping of ZnO : Cu specimens with Al increased the carrier concentration by three orders of magnitude (from 1017 to 1020 cm−3) without altering the ferromagnetic ordering. On the other hand, a reduction in oxygen vacancies concentration brought about by high temperature annealing in oxygen had a large detrimental effect on ferromagnetism. These results tend to eliminate a free carrier mediated mechanism and point towards a defect mediated mechanism, such as a bound-magnetic-polaron mediated exchange, as being responsible for stabilizing long-range ferromagnetic ordering in these systems.}, number={24}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Chakraborti, D. and Trichy, G. R. and Prater, J. T. and Narayan, J.}, year={2007}, month={Dec}, pages={7606–7613} }