Article
Nanoscience & Nanotechnology
Yeong Jae Shin, Juan Jiang, Yichen Jia, Frederick J. Walker, Charles H. Ahn
Summary: BaTiO3 exhibits functional properties like high dielectric constant, large Pockels coefficient, and strong ferroelectricity/piezoelectricity, which can be used for various applications including non-volatile memory devices. Synthesis of BaTiO3 thin films by molecular beam epitaxy allows for growth of coherently strained and ferroelectric BaTiO3 at low temperatures, paving the way for large-scale integration with mainstream electronics platforms. Experimental results demonstrate surface mobility of BaO and TiO2 adatoms conducive to ferroelectric crystal growth at low temperatures.
Article
Nanoscience & Nanotechnology
Lili Kang, Peng Jiang, Xiaoli Zhang, Hua Hao, Xiaohong Zheng, Lei Zhang, Zhi Zeng
Summary: This study explores the quantum transport properties of 2D FTJs by constructing two different types of FTJs with partial polarization reversal to form domain walls, achieving a high TER ratio through quantum transport calculations. Analysis of the electronic structure reveals charge accumulation or depletion at the domain walls, leading to a giant TER ratio.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
L. N. Jiang, Yun-Peng Wang, Y. Zhu, X. F. Han
Summary: The long electrical screening length of an insulator allows changes in local ferroelectric polarization to affect the electrostatic potential across the entire insulating region, enhancing the tunneling electroresistance effect. First-principles calculations of multiferroic tunnel junctions reveal a unique local ferroelectric polarization at the interface, leading to an optimistic TER ratio.
Article
Nanoscience & Nanotechnology
Bhagwati Prasad, Vishal Thakare, Alan Kalitsov, Zimeng Zhang, Bruce Terris, Ramamoorthy Ramesh
Summary: Ferroelectric tunnel junctions (FTJs) based on Hafnia with Hf0.5Zr0.5O2 (HZO) barrier have shown great promise for non-volatile memory applications. By stabilizing the rhombohedral polar phase of HZO through a large compressive strain, robust ferroelectricity was achieved with approximately 1 nm thick films grown epitaxially on a SrTiO3 (001) substrate, leading to improved signal-to-noise ratio during read operations.
ADVANCED ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Natalia Andreeva, Anatoliy Petukhov, Oleg Vilkov, Adrian Petraru, Victor Luchinin
Summary: The study uses scanning tunneling spectroscopy in ultrahigh vacuum conditions and conductive atomic-force microscopy in ambient conditions to investigate the local electroresistive properties of ferroelectric tunnel junctions. The experimental current-voltage characteristics show dependence on the measurement technique applied, as the screening conditions of the polarization charges differ for the two scanning probe techniques. Additionally, the asymmetry of the tunnel barrier height for opposite ferroelectric polarization orientations may be influenced by the method used to study local tunnel electroresistance.
Article
Chemistry, Multidisciplinary
Dahye Kim, Jihyung Kim, Seokyeon Yun, Jungwoo Lee, Euncho Seo, Sungjun Kim
Summary: This paper proposes a ferroelectric tunnel junction using hafnium aluminum oxide as the ferroelectric layer, and demonstrates its capability as a synaptic device through electrical analysis and experiments. The maximum remanent polarization and threshold electric field values are evaluated for different device conditions. Furthermore, the study shows that the hafnium aluminum oxide-based junction can exhibit synaptic plasticity and be utilized for reservoir computing. The synaptic properties of the ferroelectric tunnel junction are verified for the feasibility of its implementation as an artificial synaptic device.
Article
Chemistry, Physical
Minghao Liu, Ting Liao, Ziqi Sun, Yuantong Gu, Liangzhi Kou
Summary: Two-dimensional ferroelectric materials are considered promising for high-performance nanoelectronic devices due to their bistable and switchable polarization states which provide non-volatility, high storage density, low energy cost, and short response time. This mini review discusses the mechanism and operation principles of ferroelectric devices and summarizes the latest research progress on electronic devices based on 2D ferroelectrics, providing perspectives for future research and development directions in various fields. This overview aims to highlight the application of 2D ferroelectrics in electronic devices.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Hui Gan, Shengchun Shen, Yaoxin Li, Yuewei Yin, Xiaoguang Li
Summary: We find that the electronic structures and transport properties of ferroelectric tunnel junctions (FTJs) are highly influenced by the types and locations of oxygen vacancies (OVs) in the ferroelectric barrier. The presence of OVs leads to the formation of local tail-to-tail domain walls, which alters the ferroelectricity of the barrier and the local density of states in the TiO2 layers. Consequently, the tunneling electroresistance (TER) effect is enhanced in the presence of OVs and is sensitive to their types and locations. These findings are crucial for the design of FTJs.
Article
Chemistry, Physical
Jin Yuan, Jian-Qing Dai, Miao-Wei Zhao
Summary: This study theoretically demonstrates that Pt/BiAlO3/Pt (Pt/BAO/Pt) structures can achieve a giant tunneling electroresistance (TER) effect, comparable to van der Waals tunnel junctions, by switching the electric polarization of the ferroelectric barrier. Furthermore, the use of a graphene monolayer can enhance the TER effect and improve the writing endurance of FTJ memories.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Yongqi Ruan, Qi Zhang, Michael Lord, Yizhong Guo, Jinzhao Wang, Jiaolian Liu, Zhijun Ma, Peng Zhou, Tianjin Zhang, Nagarajan Valanoor
Summary: This study investigates the current-voltage (I-V) characteristics and ON/OFF ratio in hafnium oxide (HfO2)-based ferroelectric tunnel junctions (FTJs) under different poling sequences. The results show that the ON/OFF ratio doubles when a -5 V poling pulse is applied prior to a +5 V pulse. It is also found that the ON-state exhibits Ohmic behavior while the OFF-state shows nonlinearity, indicating direct tunneling across a barrier. The study explains the poling sequence-dependent tunneling electroresistance by the evolution of domain structure in the ferroelectric films.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Liming Chen, Jian Zhou, Xiao Zhang, Kuankuan Ding, Jianxiang Ding, Zhengming Sun, Xuefeng Wang
Summary: This study investigates the influence of quantum interference effects on tunneling electroresistance in La0.7Sr0.3MnO3/BaTiO3/Nb:SrTiO3 FTJs at low temperatures. It is found that the ON/OFF current ratio can be significantly enhanced by manipulating the ferroelectric polarization effect.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
L. N. Jiang, Yun-Peng Wang, W. Z. Chen, X. F. Han
Summary: The high tunneling electroresistance (TER) effect in multiferroic tunnel junctions can be enhanced through interface engineering by manipulating the interfacial ferroelectric displacement to modulate the tunnel barrier width and efficiency. This revealed principle provides a novel route for enhancing TER effect through interface engineering.
Article
Materials Science, Multidisciplinary
Qinqin Wang, Ti Xie, Nicholas A. Blumenschein, Zhihao Song, Aubrey T. Hanbicki, Michael A. Susner, Benjamin S. Conner, Tony Low, Jian-Ping Wang, Adam L. Friedman, Cheng Gong
Summary: This study demonstrates high-performance FTJs constructed with graphene and a two-dimensional ferroelectric material, showing high tunneling electroresistance and gate tunability. This structure has potential applications in energy-efficient non-volatile memories and computing.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Xinzhe Du, Haoyang Sun, He Wang, Jiachen Li, Yuewei Yin, Xiaoguang Li
Summary: Hf0.5Zr0.5O2-based ferroelectric tunnel junction (FTJ) memristor exhibits high-speed switching of 20 ns, a giant electroresistance ratio of around 834, and good retention exceeding 10(4) s, with multiple states of 8 or three bits. As a solid synaptic device, adjustable synapse functions such as long-term potentiation, long-term depression, and spike-timing-dependent plasticity have been achieved.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Physics, Multidisciplinary
Yucheng Jiang, Xinglong Ma, Lin Wang, Jinlei Zhang, Zhichao Wang, Run Zhao, Guozhen Liu, Yang Li, Cheng Zhang, Chunlan Ma, Yaping Qi, Lin Wu, Ju Gao
Summary: In this study, the interfacial polarization hysteresis (IPH) is reported in vertical sidewall van der Waals heterojunctions of black phosphorus and quasi-two-dimensional electron gas on SrTiO3. Nonvolatile switching of electric polarization can be achieved by reconstructing the space charge region. The electric-field controllable IPH is experimentally verified and transitions at temperatures of 340 K and 230 K are observed.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Kitae Eom, Hanjong Paik, Jinsol Seo, Neil Campbell, Evgeny Y. Tsymbal, Sang Ho Oh, Mark S. Rzchowski, Darrell G. Schlom, Chang-Beom Eom
Summary: This study reports the formation of 2-dimensional electron gases (2DEGs) with high mobility at room temperature at the LaScO3/BaSnO3 interface. By reducing the dislocation density and obtaining an atomically flat surface through specific treatment methods, an order of magnitude higher mobility at room temperature than previously achieved is achieved. This work opens up new possibilities for exploring the exciting physics of stannate-based 2DEGs at temperatures relevant to applications in oxide nanoelectronics.
Article
Chemistry, Multidisciplinary
Kai Huang, Ding-Fu Shao, Evgeny Y. Tsymbal
Summary: In this study, we demonstrate the electrical control of DMI and magnetic skyrmions in a Fe3GeTe2 monolayer through the ferroelectric polarization of an adjacent 2D vdW ferroelectric In2Se3. The results show that the magnitude and sign of DMI can be controlled by ferroelectric polarization reversal, leading to the creation and annihilation of skyrmions.
Article
Physics, Multidisciplinary
Jianting Dong, Xinlu Li, Gautam Gurung, Meng Zhu, Peina Zhang, Fanxing Zheng, Evgeny Y. Tsymbal, Jia Zhang
Summary: Antiferromagnetic spintronics is a subfield of spintronics that takes advantage of antiferromagnets producing no stray fields and exhibiting ultrafast magnetization dynamics. This study demonstrates the potential of utilizing noncollinear antiferromagnetic metals to achieve high tunneling magnetoresistance (TMR) effect, which can be used to detect the Néel vector and produce multiple nonvolatile resistance states.
PHYSICAL REVIEW LETTERS
(2022)
Article
Nanoscience & Nanotechnology
S. Ryu, H. Zhou, T. R. Paudel, N. Campbell, J. Podkaminer, C. W. Bark, T. Hernandez, D. D. Fong, Y. Zhang, L. Xie, X. Q. Pan, E. Y. Tsymbal, M. S. Rzchowski, C. B. Eom
Summary: Atomic flat (111) interfaces between insulating perovskite oxides provide a landscape for new electronic phenomena, such as graphene-like coordination between interfacial metallic ion layer pairs leading to topologically protected states. In this study, epitaxial heterostructures of (111)-oriented LaAlO3/SrTiO3 (LAO/STO) were investigated, and it was found that the LAO overlayer eliminates the structural reconstruction of the STO (111) surface through an electronic reconstruction, determining the properties of the resulting two-dimensional conducting gas.
Article
Engineering, Electrical & Electronic
Arnab Bose, Nathaniel J. Schreiber, Rakshit Jain, Ding-Fu Shao, Hari P. Nair, Jiaxin Sun, Xiyue S. Zhang, David A. Muller, Evgeny Y. Tsymbal, Darrell G. Schlom, Daniel C. Ralph
Summary: Symmetry plays a central role in determining the polarization of spin currents induced by electric fields. In this study, an out-of-plane damping-like torque is shown to be generated in RuO2/permalloy devices when the Neel vector of the collinear antiferromagnet RuO2 is canted relative to the sample plane. By measuring characteristic changes in the electric-field-induced torque vector, it is found that RuO2 generates a spin current with a well-defined tilted spin orientation parallel to the Neel vector. This antiferromagnetic spin Hall effect has distinct symmetries from other mechanisms of spin-current generation reported in antiferromagnetic and ferromagnetic materials.
NATURE ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Alexey Lipatov, Pradeep Chaudhary, Zhao Guan, Haidong Lu, Gang Li, Olivier Cregut, Kokou Dodzi Dorkenoo, Roger Proksch, Salia Cherifi-Hertel, Ding-Fu Shao, Evgeny Y. Tsymbal, Jorge Iniguez, Alexander Sinitskii, Alexei Gruverman
Summary: Recent theoretical predictions have suggested that two-dimensional van der Waals materials may exhibit ferroelectric properties, opening up exciting possibilities for scalable low-power electronic devices. Experimental evidence of polarization response has been observed in narrow-band semiconductors and semimetals known as transition metal chalcogenides (TMCs), with molybdenum disulfide (MoS2) being one of the most promising 2D electronic materials. However, despite theoretical predictions, no ferroelectricity has been experimentally detected in MoS2, although its emergence could enhance its potential for electronics applications.
NPJ 2D MATERIALS AND APPLICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Zhijun Ma, Qi Zhang, Lingling Tao, Yihao Wang, Daniel Sando, Jinling Zhou, Yizhong Guo, Michael Lord, Peng Zhou, Yongqi Ruan, Zhiwei Wang, Alex Hamilton, Alexei Gruverman, Evgeny Y. Tsymbal, Tianjin Zhang, Nagarajan Valanoor
Summary: Resonant tunneling and negative differential resistance behaviors modulated by ferroelectricity have been demonstrated in perovskite-oxide quantum well structures, paving the way for ferroelectric-based quantum-tunneling devices in future oxide electronics.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Zhongran Liu, Han Wang, Ming Li, Lingling Tao, Tula R. Paudel, Hongyang Yu, Yuxuan Wang, Siyuan Hong, Meng Zhang, Zhaohui Ren, Yanwu Xie, Evgeny Y. Tsymbal, Jingsheng Chen, Ze Zhang, He Tian
Summary: Domain-wall nanoelectronics is a new paradigm for non-volatile memory and logic technologies, where domain walls serve as an active element. Charged domain walls in ferroelectric structures have unique electronic and transport properties, which are useful for various nanoelectronics applications. In this study, a strategy for controllable creation and manipulation of charged domain walls in BiFeO3 ferroelectric films is reported, and their functionality as a memristor a few unit cells thick is demonstrated.
Article
Chemistry, Physical
Zifang Liu, Pengfei Hou, Lizhong Sun, Evgeny Y. Tsymbal, Jie Jiang, Qiong Yang
Summary: In this work, a two-dimensional van der Waals heterostructure composed of an alpha-In2Se3 ferroelectric and a hexagonal IV-VI semiconductor is designed, and an in-plane ferroelectric tunnel junction based on these heterostructures is proposed. First-principles calculations show that the electronic band structure of the designed heterostructures can be switched between insulating and metallic states by ferroelectric polarization. It is demonstrated that the in-plane ferroelectric tunnel junction exhibits two distinct transport regimes, tunneling and metallic, for OFF and ON states, respectively, resulting in a giant tunneling electroresistance effect with the OFF/ON resistance ratio exceeding 1 x 10(4). The results provide a promising approach for high-density ferroelectric memory based on 2D ferroelectric/semiconductor heterostructures.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Physical
D. C. Mahendra, Ding-Fu Shao, Vincent D. -H. Hou, Arturas Vailionis, P. Quarterman, Ali Habiboglu, M. B. Venuti, Fen Xue, Yen-Lin Huang, Chien-Min Lee, Masashi Miura, Brian Kirby, Chong Bi, Xiang Li, Yong Deng, Shy-Jay Lin, Wilman Tsai, Serena Eley, Wei-Gang Wang, Julie A. Borchers, Evgeny Y. Tsymbal, Shan X. Wang
Summary: By utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate, the authors observed both conventional spin-orbit torques and unconventional out-of-plane and in-plane anti-damping-like torques in MnPd3/CoFeB heterostructures, enabling complete field-free switching of perpendicular cobalt. These unconventional torques are attributed to the low symmetry of the (114)-oriented MnPd3 films. The results provide a path towards practical spin channels in ultrafast magnetic memory and logic devices.
Article
Physics, Multidisciplinary
Haoying Sun, Jiahui Gu, Yongqiang Li, Tula R. Paudel, Di Liu, Jierong Wang, Yipeng Zang, Chengyi Gu, Jiangfeng Yang, Wenjie Sun, Zhengbin Gu, Evgeny Y. Tsymbal, Junming Liu, Houbing Huang, Di Wu, Yuefeng Nie
Summary: By applying uniaxial strain, we achieved pure in-plane polarized ferroelectricity in ultrathin SrTiO3 membranes, which allows for the investigation of ferroelectric size effects without the interference of the depolarization field. Our study reveals that the stability of ferroelectricity is influenced by the thickness-dependent dipole-dipole interactions within the transverse Ising model.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Shu Shi, Haolong Xi, Tengfei Cao, Weinan Lin, Zhongran Liu, Jiangzhen Niu, Da Lan, Chenghang Zhou, Jing Cao, Hanxin Su, Tieyang Zhao, Ping Yang, Yao Zhu, Xiaobing Yan, Evgeny Y. Tsymbal, He Tian, Jingsheng Chen
Summary: The authors demonstrate the stabilization of the metastable orthorhombic phase in Hf0.5 Zr0.5O2 films through interface engineering and hole doping.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
L. L. Tao, Jiayu Li, Yuntian Liu, Xianjie Wang, Yu Sui, Bo Song, M. Ye. Zhuravlev, Qihang Liu
Summary: This article investigates the Rashba spin splitting phenomenon around non-time-reversal-invariant momenta and elucidates its microscopic origin. It is found that certain Bloch wave functions in specific non-invariant momentum regions can eliminate the first-order spin-orbit coupling effect, resulting in a tiny spin-orbit gap and helical spin texture. Furthermore, this quasi-symmetry-induced tiny gap can exhibit large Berry curvature, making it desirable for various topological applications. The study expands the concept of Rashba physics and paves the way for designing novel spin-splitting materials through the cooperation of symmetry and orbital engineering.
Article
Materials Science, Multidisciplinary
L. L. Tao, Qin Zhang, Huinan Li, Xianjie Wang, Yi Wang, Yu Sui, Bo Song, M. Ye. Zhuravlev
Summary: Quasisymmetry is an approximate symmetry that emerges in low-energy effective theory and commutes with the Hamiltonian at a lower order. It adds desirable properties to the system, such as large Berry curvatures due to small band gaps, which are robust against perturbations.
Article
Materials Science, Multidisciplinary
Ding-Fu Shao, Shu-Hui Zhang, Rui-Chun Xiao, Zi-An Wang, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal
Summary: In this study, we demonstrate the realization of a spin-neutral tunneling anomalous Hall effect (TAHE) in an antiferromagnetic (AFM) tunnel junction driven by spin-neutral currents. We show that the symmetry mismatch between the AFM electrode and the nonmagnetic barrier with strong spin-orbit coupling (SOC) results in spin-dependent momentum filtering, generating transverse Hall currents in each electrode. This finding opens up new possibilities for research in magnetoelectronics and spintronics.