Exploitable magnetic anisotropy and half-metallicity controls in multiferroic van der Waals heterostructure 

Yaping Wang, Xinguang Xu，Weixiao Ji，Shengshi Li，Yanlu Li & Xian Zhao 

npj Computational Materials 9: 223 (2023)

doi.org/10.1038/s41524-023-01178-2

Published online: 15 December 2023

编辑概述

多铁范德华异质结的魅力：XY磁体变身

以面内磁化为特征的二维XY铁磁体的磁有序易受到热扰动的影响，这在一定程度上限制了XY铁磁体在自旋电子学中的应用。该研究提出了一种构建多铁范德华异质结的方案，通过翻转铁电材料的极化方向可以实现XY铁磁体向海森堡铁磁体转变，同时还将进一步调控铁磁体的电子性质。来自山东大学晶体材料国家重点实验室的赵显教授、李妍璐教授和济南大学自旋电子学研究所的李胜世科研团队以XY铁磁单层VBi₂Te₄为对象与铁电单层In₂Se₃组合构建了多铁范德华异质结，实现了铁电极化对单层VBi₂Te₄中磁各向异性与电子性质的双重调控。随着In₂Se₃的极化方向由上到下的翻转，VBi₂Te₄的易磁轴将经历从面内到面外的转变，并且伴随着半导体到半金属的相变。通过二阶微扰理论、能带对齐和界面电荷转移定性的解释了VBi₂Te₄中铁电控制的面外磁各向异性和半金属性。基于多铁范德华异质结中优异的磁电耦合效应，设计了一种非易失的、高密度的、可电写电读的数据存储器件。除此之外，多铁范德华异质结构中单层VBi₂Te₄的半金属性质和磁晶各向异性能可以通过应变工程进行有效的调控。该研究极大地促进了多铁范德华异质结在先进自旋电子器件中的应用。

Editorial Summary

Transformation of XY ferromagnets: heterojunction with ferroelectric materials

The magnetic order of two-dimensional XY ferromagnets, characterized by in-plane magnetization, is susceptible to thermal perturbations, thereby limiting the application of XY ferromagnets in spintronics to some extent. This study proposes a scheme for constructing a multiferroic van der Waals (vdW) heterostructure that enables the transformation of an XY ferromagnet into a Heisenberg ferromagnet by reversing the polarization direction of the ferroelectric material, while simultaneously manipulating the electronic properties of the ferromagnet. The research team of Professor Xian Zhao and Professor Yanlu Li from the State Key Laboratory of Crystal Materials of Shandong University, along with Shengshi Li from the Spintronic Institute of Jinan University, has combined the XY ferromagnet VBi₂Te₄ monolayer with the ferroelectric In₂Se₃ monolayer to construct a multiferroic vdW heterostructure. Importantly, this allows for dual regulation of magnetic anisotropy and electronic properties in the VBi₂Te₄ monolayer by ferroelectric polarization. The reversal of the polarization direction from upward to downward in In₂Se₃can induce a transition in the easy magnetization axis of VBi₂Te₄from in-plane to out-of-plane, accompanied by a phase transition from semiconductor to half-metal for VBi₂Te₄. The ferroelectric-controlled out-of-plane magnetic anisotropy and half-metallic property in VBi₂Te₄are qualitatively explained by second-order perturbation theory, band alignment and interfacial charge transfer.Utilizing the remarkable magnetoelectric coupling effect, a non-volatile, high-density data storage device is designed based on the multiferroic vdW heterostructure, enabling electrical writing and reading. Meanwhile, the half-metallicity and magnetocrystalline anisotropy energy of the VBi₂Te₄ monolayer can be effectively tuned by strain engineering. This research significantly advances the application of the multiferroic vdW heterostructure in advanced spintronic devices.