Linker Thomas M, Nomura Ken-Ichi, Fukushima Shogo, Kalia Rajiv K, Krishnamoorthy Aravind, Nakano Aiichiro, Shimamura Kohei, Shimojo Fuyuki, Vashishta Priya
Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, United States.
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Nano Lett. 2023 Aug 23;23(16):7456-7462. doi: 10.1021/acs.nanolett.3c01885. Epub 2023 Aug 9.
We have developed an extension of the Neural Network Quantum Molecular Dynamics (NNQMD) simulation method to incorporate electric-field dynamics based on Born effective charge (BEC), called NNQMD-BEC. We first validate NNQMD-BEC for the switching mechanisms of archetypal ferroelectric PbTiO bulk crystal and 180° domain walls (DWs). NNQMD-BEC simulations correctly describe the nucleation-and-growth mechanism during DW switching. In triaxially strained PbTiO with strain conditions commonly seen in many superlattice configurations, we find that flux-closure texture can be induced with application of an electric field perpendicular to the original polarization direction. Upon field reversal, the flux-closure texture switches via a pair of transient vortices as the intermediate state, indicating an energy-efficient switching pathway. Our NNQMD-BEC method provides a theoretical guidance to study electro-mechano effects with existing machine learning force fields using a simple BEC extension, which will be relevant for engineering applications such as field-controlled switching in mechanically strained ferroelectric devices.
我们开发了一种神经网络量子分子动力学（NNQMD）模拟方法的扩展，以纳入基于玻恩有效电荷（BEC）的电场动力学，称为NNQMD-BEC。我们首先针对典型铁电体PbTiO块状晶体和180°畴壁（DWs）的开关机制对NNQMD-BEC进行了验证。NNQMD-BEC模拟正确地描述了DW开关过程中的成核和生长机制。在许多超晶格构型中常见应变条件的三轴应变PbTiO中，我们发现，施加垂直于原始极化方向的电场可以诱导磁通闭合织构。在电场反转时，磁通闭合织构通过一对瞬态涡旋作为中间状态进行切换，这表明存在一条节能的开关途径。我们的NNQMD-BEC方法通过一个简单的BEC扩展，为使用现有机器学习力场研究机电效应提供了理论指导，这将与诸如机械应变铁电器件中的场控开关等工程应用相关。
