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Articles 1 - 18 of 18
Full-Text Articles in Physics
Tunable Two-Dimensional Dirac Nodal Nets, Ding-Fu Shao, Shu-Hui Zhang, Xiaoqian Dang, Evgeny Y. Tsymbal
Tunable Two-Dimensional Dirac Nodal Nets, Ding-Fu Shao, Shu-Hui Zhang, Xiaoqian Dang, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Nodal-line semimetals are characterized by symmetry-protected band crossing lines and are expected to exhibit nontrivial electronic properties. Connections of the multiple nodal lines, resulting in nodal nets, chains, or links, are envisioned to produce even more exotic quantum states. In this work, we propose a feasible approach to realize tunable nodal-line connections in real materials. We show that certain space group symmetries support the coexistence of the planar symmetry-enforced and accidental nodal lines, which are robust to spin-orbit coupling and can be tailored into intricate patterns by chemical substitution, pressure, or strain. Based on first-principles calculations, we identify nonsymmorphic centrosymmetric …
Two-Dimensional Type-Ii Dirac Fermions In A Laalo3/Lanio3/Laalo3 Quantum Well, L. L. Tao, Evgeny Y. Tsymbal
Two-Dimensional Type-Ii Dirac Fermions In A Laalo3/Lanio3/Laalo3 Quantum Well, L. L. Tao, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
The type-II Dirac fermions that are characterized by a tilted Dirac cone and anisotropic magnetotransport properties have been recently proposed theoretically and confirmed experimentally. Here, we predict the emergence of two-dimensional (2D) type-II Dirac fermions in LaAlO3/LaNiO3/LaAlO3 quantum-well structures. Using first-principles calculations and model analyses, we show that the Dirac points are formed at the crossing between the dx2−y2 and dz2 bands protected by the mirror symmetry. The energy position of the Dirac points can be tuned to appear at the Fermi energy by changing the quantum-well width. For …
Direct Observation Of Room-Temperature Out-Of-Plane Ferroelectricity And Tunneling Electroresistance At The Two-Dimensional Limit, H. Wang, Z R. Liu, H. Y. Yoong, Tula R. Paudel, J. X. Xia, R. Guo, W. N. Lin, P. Yang, J. Wang, G. M. Chow, T. Venkatesan, Evgeny Y. Tsymbal, H. Tian, J. S. Chen
Direct Observation Of Room-Temperature Out-Of-Plane Ferroelectricity And Tunneling Electroresistance At The Two-Dimensional Limit, H. Wang, Z R. Liu, H. Y. Yoong, Tula R. Paudel, J. X. Xia, R. Guo, W. N. Lin, P. Yang, J. Wang, G. M. Chow, T. Venkatesan, Evgeny Y. Tsymbal, H. Tian, J. S. Chen
Evgeny Tsymbal Publications
Out-of-plane ferroelectricity with a high transition temperature in nanometer-scale films is required to miniaturize electronic devices. Direct visualization of stable ferroelectric polarization and its switching behavior in atomically thick films is critical for achieving this goal. Here, ferroelectric order at room temperature in the two-dimensional limit is demonstrated in tetragonal BiFeO3 ultrathin films. Using aberration-corrected scanning transmission electron microscopy, we directly observed robust out-of-plane spontaneous polarization in one-unitcell-thick BiFeO3 films. High-resolution piezoresponse force microscopy measurements show that the polarization is stable and switchable, whereas a tunneling electroresistance effect of up to 370% is achieved in BiFeO3 films. …
Defect-Assisted Tunneling Electroresistance In Ferroelectric Tunnel Junctions, Konstantin Klyukin, L. L. Tao, Evgeny Y. Tsymbal, Vitaly Alexandrov
Defect-Assisted Tunneling Electroresistance In Ferroelectric Tunnel Junctions, Konstantin Klyukin, L. L. Tao, Evgeny Y. Tsymbal, Vitaly Alexandrov
Evgeny Tsymbal Publications
Recent experimental results have demonstrated ferroelectricity in thin films of SrTiO3 induced by antisite TiSr defects. This opens a possibility to use SrTiO3 as a barrier layer in ferroelectric tunnel junctions (FTJs)—emerging electronic devices promising for applications in nanoelectronics. Here using density functional theory combined with quantum-transport calculations applied to a prototypical Pt/SrTiO3/Pt FTJ, we demonstrate that the localized in-gap energy states produced by the antisite TiSr defects are responsible for the enhanced electron tunneling conductance which can be controlled by ferroelectric polarization. Our tight-binding modeling, which takes into account multiple defects, shows that …
Effects Of B And C Doping On Tunneling Magnetoresistance In Cofe/Mgo Magnetic Tunnel Junctions, Andy Paul Chen, John D. Burton, Evgeny Y. Tsymbal, Yuan Ping Feng, Jingsheng Chen
Effects Of B And C Doping On Tunneling Magnetoresistance In Cofe/Mgo Magnetic Tunnel Junctions, Andy Paul Chen, John D. Burton, Evgeny Y. Tsymbal, Yuan Ping Feng, Jingsheng Chen
Evgeny Tsymbal Publications
Using density-functional theory calculations, we investigate the dominant defects formed by boron (B) and carbon (C) impurities in a CoFe/MgO/CoFe magnetic tunnel junction (MTJ) and their influence on conductivity and tunneling magnetoresistance (TMR). We find that, in the O-poor conditions relevant to experiment, B forms the substitutional defect BCo and C forms the interstitial site Ci at the CoFe/MgO interface. The C-doped MTJ is predicted to have a significantly higher TMR than the B-doped MTJ. This is due to interface state densities associated with the majority spin Δ1-symmetry bands being more heavily suppressed by the B …
Persistent Spin Texture Enforced By Symmetry, L. L. Tao, Evgeny Y. Tsymbal
Persistent Spin Texture Enforced By Symmetry, L. L. Tao, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Persistent spin texture (PST) is the property of some materials to maintain a uniform spin configuration in the momentum space. This property has been predicted to support an extraordinarily long spin lifetime of carriers promising for spintronics applications. Here, we predict that there exists a class of noncentrosymmetric bulk materials, where the PST is enforced by the nonsymmorphic space group symmetry of the crystal. Around certain high symmetry points in the Brillouin zone, the sublattice degrees of freedom impose a constraint on the effective spin–orbit field, which orientation remains independent of the momentum and thus maintains the PST. We illustrate …
Ambipolar Ferromagnetism By Electrostatic Doping Of A Manganite, L. M. Zheng, X. Renshaw Wang, W. M. Lü, C. J. Li, Tula R. Paudel, Z. Q. Liu, Z. Huang, S. W. Zeng, Kun Han, Z. H. Chen, X. P. Qiu, M. S. Li, Shize Yang, B. Yang, Matthew F. Chisholm, L. W. Martin, S. J. Pennycook, Evgeny Y. Tsymbal, J. M. D. Coey, W. W. Cao
Ambipolar Ferromagnetism By Electrostatic Doping Of A Manganite, L. M. Zheng, X. Renshaw Wang, W. M. Lü, C. J. Li, Tula R. Paudel, Z. Q. Liu, Z. Huang, S. W. Zeng, Kun Han, Z. H. Chen, X. P. Qiu, M. S. Li, Shize Yang, B. Yang, Matthew F. Chisholm, L. W. Martin, S. J. Pennycook, Evgeny Y. Tsymbal, J. M. D. Coey, W. W. Cao
Evgeny Tsymbal Publications
Complex-oxide materials exhibit physical properties that involve the interplay of charge and spin degrees of freedom. However, an ambipolar oxide that is able to exhibit both electron-doped and hole-doped ferromagnetism in the same material has proved elusive. Here we report ambipolar ferromagnetism in LaMnO3, with electron–hole asymmetry of the ferromagnetic order. Starting from an undoped atomically thin LaMnO3 film, we electrostatically dope the material with electrons or holes according to the polarity of a voltage applied across an ionic liquid gate. Magnetotransport characterization reveals that an increase of either electron-doping or hole-doping induced ferromagnetic order in this …
Resonant Tunneling Across A Ferroelectric Domain Wall, M. Li, L. L. Tao, J. P. Velev, Evgeny Y. Tsymbal
Resonant Tunneling Across A Ferroelectric Domain Wall, M. Li, L. L. Tao, J. P. Velev, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Motivated by recent experimental observations, we explore electron transport properties of a ferroelectric tunnel junction (FTJ) with an embedded head-to-head ferroelectric domain wall, using first-principles density-functional theory calculations. We consider a FTJ with La0.5Sr0.5MnO3 electrodes separated by a BaTiO3 barrier layer and show that an in-plane charged domain wall in the ferroelectric BaTiO3 can be induced by polar interfaces. The resulting V-shaped electrostatic potential profile across the BaTiO3 layer creates a quantum well and leads to the formation of a two-dimensional electron gas, which stabilizes the domain wall. The confined electronic states …
Polarization-Controlled Modulation Doping Of A Ferroelectric From First Principles, Xiaohui Liu, Evgeny Y. Tsymbal, Karin M. Rabe
Polarization-Controlled Modulation Doping Of A Ferroelectric From First Principles, Xiaohui Liu, Evgeny Y. Tsymbal, Karin M. Rabe
Evgeny Tsymbal Publications
In a ferroelectric field effect transistor (FeFET), it is generally assumed that the ferroelectric gate plays a purely electrostatic role. Recently it has been shown that in some cases, which could be called “active FeFETs,” electronic states in the ferroelectric contribute to the device conductance as the result of a modulation doping effect in which carriers are transferred from the channel into the ferroelectric layers near the interface. Here we report first-principles calculations and model analysis to elucidate the various aspects of this mechanism and to provide guidance in materials choices and interface termination for optimizing the on-off ratio, using …
Isostructural Metal-Insulator Transition In Vo2, D. Lee, B. Chung, Y. Shi, G.-Y. Kim, N. Campbell, F. Xue, K. Song, S.-Y. Choi, J. P. Podkaminer, T. H. Kim, P. J. Ryan, J.-W. Kim, T. R. Paudel, J.-H. Kang, J. W. Spinuzzi, D. A. Tenne, E. Y. Tsymbal, M. S. Rzchowski, L. Q. Chen, J. Lee, And C. B. Eom
Isostructural Metal-Insulator Transition In Vo2, D. Lee, B. Chung, Y. Shi, G.-Y. Kim, N. Campbell, F. Xue, K. Song, S.-Y. Choi, J. P. Podkaminer, T. H. Kim, P. J. Ryan, J.-W. Kim, T. R. Paudel, J.-H. Kang, J. W. Spinuzzi, D. A. Tenne, E. Y. Tsymbal, M. S. Rzchowski, L. Q. Chen, J. Lee, And C. B. Eom
Evgeny Tsymbal Publications
No abstract provided.
Tunneling Anomalous Hall Effect In A Ferroelectric Tunnel Junction, M. Y. Zhuravlev, A. Alexandrov, L. L. Tao, And E. Y. Tsymbal
Tunneling Anomalous Hall Effect In A Ferroelectric Tunnel Junction, M. Y. Zhuravlev, A. Alexandrov, L. L. Tao, And E. Y. Tsymbal
Evgeny Tsymbal Publications
No abstract provided.
Direct Observation Of A Two-Dimensional Hole Gas At Oxide Interfaces, H. Lee, N. Campbell, J. Lee, T. Asel, T. Paudel, H. Zhou, J. W. Lee, B. Noesges, J. Seo, B. Park, L. J. Brillson, S. H. Oh, E. Y. Tsymbal, M. S. Rzchowski, And C. B. Eom
Direct Observation Of A Two-Dimensional Hole Gas At Oxide Interfaces, H. Lee, N. Campbell, J. Lee, T. Asel, T. Paudel, H. Zhou, J. W. Lee, B. Noesges, J. Seo, B. Park, L. J. Brillson, S. H. Oh, E. Y. Tsymbal, M. S. Rzchowski, And C. B. Eom
Evgeny Tsymbal Publications
No abstract provided.
Anisotropic Polarization-Induced Conduction At The Ferroelectric/Insulator Interface, Y. Zhang, H. Lu, L. Xie, X. Yan, T. R. Paudel, J. Kim, X. Chen, H. Wang, C. Heikes, L. Li, M. Xu, D. G. Schlom, L.-Q. Chen, R. Wu, E. Y. Tsymbal, A. Gruverman, And X. Q. Pan
Anisotropic Polarization-Induced Conduction At The Ferroelectric/Insulator Interface, Y. Zhang, H. Lu, L. Xie, X. Yan, T. R. Paudel, J. Kim, X. Chen, H. Wang, C. Heikes, L. Li, M. Xu, D. G. Schlom, L.-Q. Chen, R. Wu, E. Y. Tsymbal, A. Gruverman, And X. Q. Pan
Evgeny Tsymbal Publications
No abstract provided.
Direct Imaging Of The Electron Liquid At Oxide Interfaces, Kyung Song, Sangwoo Ryu, Hyungwoo Lee, Tula R. Paudel, Christoph T. Koch, Bumsu Park, Ja Kyung Lee, Si-Young Choi, Young-Min Kim, Jong Chan Kim, Hu Young Jeong, Mark S. Rzchowski, Evgeny Y. Tsymbal, Chang-Beom Eom, And Sang Ho Oh
Direct Imaging Of The Electron Liquid At Oxide Interfaces, Kyung Song, Sangwoo Ryu, Hyungwoo Lee, Tula R. Paudel, Christoph T. Koch, Bumsu Park, Ja Kyung Lee, Si-Young Choi, Young-Min Kim, Jong Chan Kim, Hu Young Jeong, Mark S. Rzchowski, Evgeny Y. Tsymbal, Chang-Beom Eom, And Sang Ho Oh
Evgeny Tsymbal Publications
No abstract provided.
Tunneling Hot Spots In Ferroelectric Srtio3, Haidong Lu, Daesu Lee, Konstantin Klyukin, Lingling Tao, Bo Wang, Hyungwoo Lee, Tula R. Paudel, Long-Qing Chen, Evgeny Y. Tsymbal, Vitaly Alexandrov, Chang-Beom Eom, And Alexei Gruverman
Tunneling Hot Spots In Ferroelectric Srtio3, Haidong Lu, Daesu Lee, Konstantin Klyukin, Lingling Tao, Bo Wang, Hyungwoo Lee, Tula R. Paudel, Long-Qing Chen, Evgeny Y. Tsymbal, Vitaly Alexandrov, Chang-Beom Eom, And Alexei Gruverman
Evgeny Tsymbal Publications
No abstract provided.
X-Ray-Induced Colossal Persistent Photoconductivity In Current-Perpendicular-To-Plane Thin-Film Junctions, Wei Jin Hu, Tula R. Paudel, Sergei Lopatin, Zhihong Wang, He Ma, Kewei Wu, Ashok Bera, Guoliang Yuan, Alexei Gruverman, Evgeny Y. Tsymbal, And Tom Wu
X-Ray-Induced Colossal Persistent Photoconductivity In Current-Perpendicular-To-Plane Thin-Film Junctions, Wei Jin Hu, Tula R. Paudel, Sergei Lopatin, Zhihong Wang, He Ma, Kewei Wu, Ashok Bera, Guoliang Yuan, Alexei Gruverman, Evgeny Y. Tsymbal, And Tom Wu
Evgeny Tsymbal Publications
No abstract provided.
Solid-State Synapse Based On Magnetoelectrically Coupled Memristor, Weichuan Huang, Yue-Wen Fang, Yuewei Yin, Bobo Tian, Wenbo Zhao, Chuangming Hou, Chao Ma, Qi Li, Evgeny Y. Tsymbal, Chun-Gang Duan, And Xiaoguang Li
Solid-State Synapse Based On Magnetoelectrically Coupled Memristor, Weichuan Huang, Yue-Wen Fang, Yuewei Yin, Bobo Tian, Wenbo Zhao, Chuangming Hou, Chao Ma, Qi Li, Evgeny Y. Tsymbal, Chun-Gang Duan, And Xiaoguang Li
Evgeny Tsymbal Publications
No abstract provided.
Contributions Of The Lead-Bromine Weighted Bulk Bands To The Occupied Density Of States Of The Hybrid Tri-Bromide Perovskites, A. R. Kirmani, A. E. Mansour, M. I. Saidaminov, X. Cui, D. Shi, A. Alofi, Y. Losovyj, G. Gurung, T. R. Paudel, A. J. Yost, P. A. Dowben, E. Y. Tsymbal, A. Amassian, And K. Katsiev
Contributions Of The Lead-Bromine Weighted Bulk Bands To The Occupied Density Of States Of The Hybrid Tri-Bromide Perovskites, A. R. Kirmani, A. E. Mansour, M. I. Saidaminov, X. Cui, D. Shi, A. Alofi, Y. Losovyj, G. Gurung, T. R. Paudel, A. J. Yost, P. A. Dowben, E. Y. Tsymbal, A. Amassian, And K. Katsiev
Evgeny Tsymbal Publications
No abstract provided.