Recently, a method of ultrafast polarization switching in ferroelectrics has been suggested. The basic idea of the method is to employ the effect of self-acceleration of polarization dynamics due to a resonator feedback field. This is the idea of principle whose efficiency is demonstrated by an Ising-type model in a transverse field. Of course, the practical realization of the method requires the choice of appropriate materials, which is a separate problem. For example, the standard order-disorder ferroelectrics with spatially symmetric double-well potentials cannot be used for this purpose, since, because of the symmetry, they lack the transverse polarization. However, ferroelectrics with asymmetric potentials, possessing this polarization, can be used. Moreover, if the potential asymmetry, hence the transverse polarization, could be regulated, e.g., by shear stress or shear strain, this could provide a tool for governing the process of polarization switching.
We investigate the role of polarization-photon coupling (specifically, polarization-oscillation-induced radiation electric field) in the excitation of ferroelectric thin films by an ultrafast terahertz (THz) electric-field pulse. Analytical theory is developed to predict how the frequencies and relaxation time of three-dimensional soft mode phonons (intrinsic polarization oscillation) are modulated by radiation electric field and epitaxial strain. Ultrafast THz-pulse-driven excitation of harmonic polarization oscillation in strained single-domain ferroelectric thin film is then simulated using…
In spintronics, it is important to be able to manipulate magnetization rapidly and reliably. Several methods can control magnetization, such as by applying current pulses or magnetic fields. An applied current can reverse magnetization with nanosecond speed through the spin torque effect. For faster switching, subpicosecond switching with femtoseconds laser pulse has been achieved in amorphous rare-earth transition-metal ferrimagnets. In this study, we employed atomistic simulations to investigate ultrafast switching in a synthetic antiferromagnet with bilayer amorphous FeGd ferrimagnets. Usin…
Negative capacitance field-effect transistors (NC-FETs) have attracted wide interest as promising candidates for steep-slope devices, and sub-60 mV/decade switching has been demonstrated in NC-FETs with various device structures and material systems. However, the detailed mechanisms of the observed steep-slope switching in some of these experiments are under intense debate. Here we show that sub-60 mV/decade switching can be observed in a WS2 transistor with a metal-insulator-metal-insulator-semiconductor (MIMIS) structure - without any ferroelectric component. This structure resembles an NC-F…
Pulse-based studies of ferroelectric capacitor systems have been used by several groups to experimentally probe the mechanisms of apparent negative capacitance. In this paper, the behavior of such systems is modeled through SPICE simulation with a delayed-response Preisach model, and the results are compared to available data. It is found that a simple ferroelectric domain delay model can explain much of the observed behavior, capturing the qualitatively different effects of bipolar and unipolar switching, as well as the voltage dependence of said switching. The observed behavior and its model…
When Screening Current Controls Ferroelectric Switching: From Field-Limited to Current-Limited Regimes
CICECO Aveiro Institute of Materials & Physics Department, University of Aveiro（阿威罗大学 CICECO 材料研究所与物理系）；School of Natural Sciences and Mathematics, Ural Federal University（乌拉尔联邦大学自然科学与数学学院）
The ferroelectric polarization switching in ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2, HZO) in the HZO/Al2O3 ferroelectric/dielectric stack is investigated systematically by capacitance-voltage and polarization-voltage measurements. The thickness of dielectric layer is found to have a determinant impact on the ferroelectric polarization switching of ferroelectric HZO. A suppression of ferroelectricity is observed with thick dielectric layer. In the gate stacks with thin dielectric layers, a full polarization switching of the ferroelectric layer is found possible by the proposed leaka…
Multilevel recording in Bi-deficient Pt/BFO/SRO heterostructures based on ferroelectric resistive switching targeting high-density information storage in nonvolatile memories
Semiconducting ferroelectric materials with low energy polarisation switching offer a platform for next-generation electronics such as ferroelectric field-effect transistors. Ferroelectric domains at symmetry-broken interfaces of transition metal dichalcogenide films provide an opportunity to combine the potential of semiconducting ferroelectrics with the design flexibility of two-dimensional material devices. Here, local control of ferroelectric domains in a marginally twisted WS2 bilayer is demonstrated with a scanning tunneling microscope at room temperature, and their observed reversible e…
Ferroelectric switching control of spin current in graphene proximitized by In$_2$Se$_3$
Institute of Informatics, Slovak Academy of Sciences（斯洛伐克科学院信息学研究所）；Faculty of Physics, University of Belgrade（贝尔格莱德大学物理学院）；Institute of Physics, Pavol Jozef Šafárik University in Košice（科希策帕沃尔·约瑟夫·沙法里克大学物理研究所）；Institute of Physics, University of Silesia in Katowice（卡托维兹西里西亚大学物理研究所）；Institute of Experimental Physics, Slovak Academy of Sciences（斯洛伐克科学院实验物理研究所）；New Technologies Research Centre, University of West Bohemia（西波希米亚大学新技术研究中心）
The ability to switch between distinct states of polarization comprises the defining property of ferroelectrics. However, the microscopic mechanism responsible for switching is not well understood and theoretical estimates based on coherent monodomain switching typically overestimate experimentally determined coercive fields by orders of magnitude. In this work we present a detailed first principles characterization of domain walls (DWs) in two-dimensional ferroelectric GeS, GeSe, SnS and SnSe. In particular, we calculate the formation energies and migration barriers for 180 and 90 DWs, and th…
Shear-Mode Raman Imaging of Ferroelectric Switching in Multilayer 3$R$-MoS$_2$
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University（南京大学固体微结构物理实验室和物理系）；Research Center for Electronic and Optical Materials, National Institute for Materials Science（物质材料研究机构电子光学材料研究中心）；Research Center for Materials Nanoarchitectonics, National Institute for Materials Science（物质材料研究机构材料纳米构造研究中心）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）
Subcritical switching dynamics and humidity effects in nanoscale studies of domain growth in ferroelectric thin films
利用偏压扫描探针显微镜研究了c轴取向外延Pb（Zr $_{0.2}$ Ti $_{0.8}$）O $_3$薄膜的铁电畴反转。虽然线性和对数依赖的域大小的尖端偏置和写入时间，分别是众所周知的，我们报告了一个额外的线性依赖相对湿度在28-65%的范围内。我们映射出的开关域的大小作为一个函数的尖端偏置和施加的脉冲时间，并描述了一个生长限制制度非常短的脉冲和成核限制制度非常低的尖端偏置。使用“中断开关”的测量，我们探测的成核制度与亚临界脉冲，并确定了一个令人惊讶的长弛豫时间的顺序为100毫秒，我们涉及到离子的重新分配的表面上和薄膜本身内。
Controlling magnetism using voltage is highly desired for applications, but remains challenging due to fundamental contradiction between polarity and magnetism. Here we propose a mechanism to manipulate magnetic domain walls in ferrimagnetic or ferromagnetic multiferroics using electric field. Different from those studies based on static domain-level couplings, here the magnetoelectric coupling relies on the collaborative spin dynamics around domain walls. Accompanying the reversal of spin chirality driven by polarization switching, a "rolling-downhill"-like motion of domain wall is achieved a…
Ferroelectric switching of interfacial dipoles in $α$-RuCl$_3$/graphene heterostructure
Daegu Gyeongbuk Institute of Science and Technology (DGIST)（大邱庆北科学技术院）；Pohang University of Science and Technology（浦项科技大学）；Institute for Basic Science（基础科学研究院）；National Institute for Materials Science（国立材料研究所）；California Institute of Technology（加州理工学院）
