Npj Comput. Mater.: 多铁范德华异质结—磁各向异性与半金属性的同步调控

海归学者发起的公益学术平台

分享信息，整合资源

交流学术，偶尔风月

Fig. 1 Schematic representation of transition between 2D XY and Heisenberg models.

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设计了基于XY铁磁单层VBi₂Te₄和铁电单层In₂Se₃的多铁范德华异质结。在该异质结中，铁电层极化方向的翻转可以诱导铁磁层的易磁轴由面内转换为面外，使二维XY铁磁体转变为海森堡铁磁体，同时还实现了长程磁有序的关与开。根据蒙特卡洛模拟，具有面外磁各向异性的单层VBi₂Te₄的居里温度可达76K。此外，基于二阶微扰理论定性地解释了多铁范德华异质结中与铁电极化有关的磁各向异性。

Fig. 2 Geometric structures of free-standing monolayers and heterostructures.

值得注意的是，随着磁各向异性改变，单层VBi₂Te₄还实现了从半导体到半金属态的转变。这使得In₂Se₃的铁电极化态和VBi₂Te₄的磁各向异性都可以通过VBi₂Te₄的导电状态来进行表征。鉴于此，作者从多铁范德华异质结出发，设计了一种非易失的高密度数据存储器件。此外，研究发现，双轴应变能够有效地调控多铁范德华异质结中单层VBi₂Te₄的半金属性质和磁晶各向异性能。该研究为磁各向异性和半金属性的非易失性电调控提供了一个良好的平台，推动了多铁范德华异质结在先进自旋电子器件中的实际应用。

Fig. 6 Strain-induced change in MAE.

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 

Two-dimensional (2D) XY ferromagnets have drawn pronounced interest in recent years, but the characteristic of easy-plane magnetization restricts their application in spintronics to some extent. Here, we propose a general strategy for constructing multiferroic van der Waals heterostructures, aiming to achieve electrical control over the magnetic anisotropy in 2D XY ferromagnets. The validity of this strategy is verified by the heterostructure composed of ferromagnetic VBi2Te4 and ferroelectric In2Se3 monolayers. By manipulating the polarized states of In2Se3, the VBi2Te4 can be reversibly transformed between 2D XY and Heisenberg ferromagnets, characterized by the switching of easy magnetization axis between in-plane and out-of-plane directions. More interestingly, accompanied by the changes in magnetic anisotropy, the VBi2Te4 also demonstrates a phase transition from a semiconductor to a half-metal state, which can be ascribed to the band alignment and interfacial charge transfer. The switchable magnetic and electronic properties enable the heterostructure to be utilized in nonvolatile memory and logic devices. Additionally, the half-metallicity and magnetocrystalline anisotropy energy of the heterostructure can be effectively tuned by biaxial strain. These findings not only pave the way for electrically nonvolatile control of 2D XY ferromagnet, but also facilitate the development of interfacial magnetoelectric physics and applications.