Mehmood Nasir, Song Xiao, Tian Guo, Hou Zhipeng, Chen Deyang, Fan Zhen, Qin Minghui, Gao Xingsen, Liu Jun-Ming
Institute for Advanced Materials and Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, People's Republic of China.
J Phys Condens Matter. 2019 Jul 24;31(29):295802. doi: 10.1088/1361-648X/ab18f0. Epub 2019 Apr 12.
Electric field control of magnetic state switching mediated by magneto-elastic coupling in multiferroic heterostructures consisting of shape anisotropic magnetostrictive nanomagnets elastically coupled with a piezoelectric substrate has a promising potential for next generation magneto-elastic memory and logic devices. In this work, by using micromagnetic simulation, we showed that localized strain-induced magnetic anisotropy caused by the electric field-induced piezostrain combined with strong multifold shape anisotropy effect can be used for achieving a multistate switching of magnetization in a triangular soft magnetic nano-island on a piezoelectric substrate. A piezostrain-induced uniaxial magnetic anisotropy pulse applied in specific directions switches the magnetization within the triangular nanomagnet by an angle of 60° from the initial state. The relation between critical magnitude of the strain pulse for the switching of the magnetization states and geometric parameters (thickness and lateral size) within the triangular nanomagnets has been worked out. Complete cycles of clockwise as well as counter-clockwise switching of the magnetization states of the triangular nanomagnet have been achieved by a series of sequential switching with different directions of applied strain-induced magnetic anisotropy. This local gating scheme-based multistate switching can be used for electric field-induced ultra-fast, deterministic and reversible magnetization switching which are the key challenges in designing of the magnetoelastic and/or magnetoelectric memory and logic devices.
在由形状各向异性磁致伸缩纳米磁体与压电衬底弹性耦合构成的多铁异质结构中，通过磁弹耦合实现磁场控制的磁态切换，对于下一代磁弹性存储器和逻辑器件具有广阔的应用前景。在这项工作中，我们通过微磁模拟表明，由电场诱导的压电应变与强多重形状各向异性效应相结合所引起的局部应变诱导磁各向异性，可用于实现压电衬底上三角形软磁纳米岛中磁化强度的多态切换。在特定方向施加的压电应变诱导单轴磁各向异性脉冲，可使三角形纳米磁体内的磁化强度从初始状态转过60°角。已得出磁化状态切换所需应变脉冲的临界幅度与三角形纳米磁体内几何参数（厚度和横向尺寸）之间的关系。通过一系列具有不同施加应变诱导磁各向异性方向的顺序切换，已实现三角形纳米磁体磁化状态的顺时针和逆时针完整切换循环。这种基于局部选通方案的多态切换可用于电场诱导的超快、确定性和可逆磁化切换，而这正是磁弹性和/或磁电存储器及逻辑器件设计中的关键挑战。
