Defect-mediated vortex multiplication and annihilation in ferroelectrics and the feasibility of vortex switching by stress
Defect-mediated vortex multiplication and annihilation in ferroelectrics and the feasibility of vortex switching by stress
复制标题
铁电体中缺陷介导的涡旋倍增和湮灭以及应力涡旋切换的可行性
DOI：
10.1016/j.actamat.2018.01.018
复制
发表时间：
2018
期刊：
影响因子：
9.4
通讯作者：
Zheng Yue
中科院分区：
文献类型：
--
作者：
Yuan Shuai;Chen W. J.;Ma L. L.;Ji Ye;Xiong W. M.;Liu J. Y.;Liu Y. L.;Wang Biao;Zheng Yue
铁电体中偶极环向矩方向的切换为新型纳米级存储器和逻辑器件的开发提供了令人兴奋的机会。然而，在现阶段，实际控制涡旋手性是相当具有挑战性的，更不用说通过机械方法。在本文中，我们进行了相场模拟表明，机械开关的涡旋手性可以实现在铁电纳米片通过缺陷工程。在纳米片晶中引入空洞缺陷后，单涡态和多涡态的相对稳定性发生了变化。重要的是，在应力诱导涡增殖过程中，空穴是新涡的有利成核核心;同时，在涡湮灭过程中，涡趋于远离空穴湮灭。由于涡旋成核和湮灭的有利区域不相同，因此可以实现涡旋手征性的确定性机械切换。系统地揭示了温度、纳米片形状、空穴尺寸以及空穴位置对缺陷介导的涡旋开关行为的影响。研究结果证明了利用机械负载实现涡旋开关的可行性，为基于铁磁涡旋的机电控制和器件的开发提供了一条途径。
The possibility of switching the direction of the dipole toroidal moment in ferroelectrics provides exciting opportunities for development of novel nanoscale memory and logic devices. However, a practical control of vortex chirality is rather challenging at present stage, not to mention via mechanical methods. In this paper, we performed the phase-field simulations to show that mechanical switching of vortex chirality can be achieved in ferroelectric nanoplatelet via defect engineering. After introducing a void defect in the nanoplatelet, relative stability of single-vortex state and multi-vortices state is found to be altered. Importantly, during stress-induced vortex multiplication process, the void is a favored nucleation core of new vortex; meanwhile, vortices tend to annihilate away from the void during a vortex annihilation process. As the favored regions of vortex nucleation and annihilation are not the same, a deterministic mechanical switching of vortex chirality can be achieved. The effects of temperature, shape of the nanoplatelet, void size, as well as void position, on the defect-mediated vortex switching behaviors are systematically revealed. Our study demonstrates the feasibility of vortex switching by mechanical loads and provides a route to control and develop electromechanical devices based on ferroic vortices.