@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{li_hodak_lu_bernholc_2017, title={Selective sensing of ethylene and glucose using carbon-nanotube-based sensors: an ab initio investigation}, volume={9}, ISSN={2040-3364 2040-3372}, url={http://dx.doi.org/10.1039/C6NR07371A}, DOI={10.1039/c6nr07371a}, abstractNote={Functionalized carbon nanotubes have great potential for nanoscale sensing applications, yet many aspects of their sensing mechanisms are not understood. Here, two paradigmatic sensor configurations for detection of biologically important molecules are investigated through ab initio calculations: a non-covalently functionalized nanotube for glucose detection and a covalently functionalized nanotube for ethylene detection. Glucose and ethylene control key life processes of humans and plants, respectively, despite of their structural and chemical simplicity. The sensors' electrical conductance and transmission coefficients are evaluated at the full density-functional theory level via the non-equilibrium Green's function method. We also investigate the effects of the density of the receptors, the band gaps of the nanotubes, the source-drain voltages, and the atomic modification of the receptor on detection sensitivities. A clear atomistic picture emerges about the mechanisms involved in glucose and ethylene sensing. While semiconducting nanotubes exhibit good sensitivities in both cases, the current through metallic nanotubes is only weakly affected by analyte attachment. These quantitative results could guide the design of improved sensors.}, number={4}, journal={Nanoscale}, publisher={Royal Society of Chemistry (RSC)}, author={Li, Yan and Hodak, Miroslav and Lu, Wenchang and Bernholc, J.}, year={2017}, pages={1687–1698} }
 @article{li_hodak_lu_bernholc_2016, title={Mechanisms of NH3 and NO2 detection in carbon-nanotube-based sensors: An ab initio investigation}, volume={101}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/j.carbon.2016.01.092}, DOI={10.1016/j.carbon.2016.01.092}, abstractNote={The mechanisms of NH3 and NO2 detection by single-walled carbon nanotube-based devices are investigated by ab initio calculations and the non-equilibrium Greens function (NEGF) methodology. While both NH3 and NO2 can physisorb to a pristine carbon nanotube, we show that their adsorption only results in small current changes through the device. For a carbon nanotube (CNT) attached to gold nanowire leads, the most sensitive detection site is at the CNT near the CNT-Au contact, where chemisorption occurs. The resulting change in electron transmission and low-bias current can lead to over 30% sensitivity. While both NH3 and NO2 can also chemisorb at the Au electrodes, their adsorption results in only a small change in the plurality of the conducting levels of the gold layers, and thus a small effect on current. In order to enhance the detection sensitivity, it is thus beneficial to mask the electrodes to prevent chemisorption. Furthermore, the length of the pure CNT segment does not strongly affect the relative sensitivity. Our results suggest that a short-CNT device with exposed contact regions and masked electrodes would have the greatest sensitivity.}, journal={Carbon}, publisher={Elsevier BV}, author={Li, Yan and Hodak, Miroslav and Lu, Wenchang and Bernholc, J.}, year={2016}, month={May}, pages={177–183} }
 @article{liu_li_krause_pasquinelli_rojas_2012, title={Mesoscopic Simulations of the Phase Behavior of Aqueous EO19PO29EO19 Solutions Confined and Sheared by Hydrophobic and Hydrophilic Surfaces}, volume={4}, ISSN={["1944-8252"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863067883&partnerID=MN8TOARS}, DOI={10.1021/am200917h}, abstractNote={The MesoDyn method is used to investigate associative structures in aqueous solution of a nonionic triblock copolymer consisting of poly(propylene oxide) capped on both ends with poly(ethylene oxide) chains. The effect of adsorbing (hydrophobic) and nonadsorbing (hydrophilic) solid surfaces in contact with aqueous solutions of the polymer is elucidated. The macromolecules form self-assembled structures in solution. Confinement under shear forces is investigated in terms of interfacial behavior and association. The formation of micelles under confinement between hydrophilic surfaces occurs faster than in bulk aqueous solution while layered structures assemble when the polymers are confined between hydrophobic surfaces. Micelles are deformed under shear rates of 1 μs(-1) and eventually break to form persistent, adsorbed layered structures. As a result, surface damage under frictional forces is prevented. Overall, this study indicates that aqueous triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (Pluronics, EO(m)PO(n)EO(m)) act as a boundary lubricant for hydrophobic surfaces but not for hydrophilic ones.}, number={1}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Liu, Hongyi and Li, Yan and Krause, Wendy E. and Pasquinelli, Melissa A. and Rojas, Orlando J.}, year={2012}, month={Jan}, pages={87–95} }
 @article{liu_li_krause_rojas_pasquinelli_2012, title={The Soft-Confined Method for Creating Molecular Models of Amorphous Polymer Surfaces}, volume={116}, ISSN={["1520-6106"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84863136276&partnerID=MN8TOARS}, DOI={10.1021/jp209024r}, abstractNote={The goal of this work was to use molecular dynamics (MD) simulations to build amorphous surface layers of polypropylene (PP) and cellulose and to inspect their physical and interfacial properties. A new method to produce molecular models for these surfaces was developed, which involved the use of a "soft" confining layer comprised of a xenon crystal. This method compacts the polymers into a density distribution and a degree of molecular surface roughness that corresponds well to experimental values. In addition, calculated properties such as density, cohesive energy density, coefficient of thermal expansion, and the surface energy agree with experimental values and thus validate the use of soft confining layers. The method can be applied to polymers with a linear backbone such as PP as well as those whose backbones contain rings, such as cellulose. The developed PP and cellulose surfaces were characterized by their interactions with water. It was found that a water nanodroplet spreads on the amorphous cellulose surfaces, but there was no significant change in the dimension of the droplet on the PP surface; the resulting MD water contact angles on PP and amorphous cellulose surfaces were determined to be 106 and 33°, respectively.}, number={5}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, publisher={American Chemical Society}, author={Liu, Hongyi and Li, Yan and Krause, Wendy E. and Rojas, Orlando J. and Pasquinelli, Melissa A.}, year={2012}, month={Feb}, pages={1570–1578} }