电场可切换的层间磁序和Janus VSSe双层不同界面中的反常谷霍尔效应

中文摘要 AI 辅助

电场对磁序和谷极化的控制对于自旋电子学和谷电子学应用具有巨大潜力。然而，在二维（2D）范德瓦尔斯（vdW）磁体中实现这种电学调制仍然是一个基本挑战。在此，通过第一性原理计算，我们验证了在具有不同界面的Janus VSSe双层中可以实现电可调的层间磁序和谷极化。尽管每个组成Janus单层内的偶极矩大小相同，但双层上的垂直内建静电势差$Δϕ$强烈依赖于这些偶极子的取向，这源于不同的界面构型。因此，具有不同界面的VSSe双层具有不同的层间磁耦合，并对外部电场表现出显著不同的响应。对于Se-S界面，由于巡游电子介导的铁磁（FM）交换耦合与由界面Se和S原子介导的层间$Δϕ$依赖的反铁磁（AFM）/FM超超交换相互作用之间的竞争，可以实现反铁磁（AFM）和铁磁（FM）状态之间的可逆电场切换。对于Se-Se界面，谷极化和自旋分裂都可以通过面外电场有效反转，实现全电场控制的反常谷霍尔效应。我们的结果表明，磁性Janus双层的界面可以作为额外的自由度来调节2D vdW材料中的电子、磁性和谷性质。Janus VSSe双层被认为是设计低功耗自旋电子学和谷电子学器件的有前景的平台。

英文摘要

Electric-field control of magnetic order and valley polarization holds great promise for spintronic and valleytronic applications. However, achieving such electrical modulation remains a fundamental challenge in two-dimensional (2D) van der Waals (vdW) magnets. Herein, via first-principles calculations, we verify that electrically tunable interlayer magnetic order and valley polarization can be realized in Janus VSSe bilayers with different interfaces. Although the magnitudes of dipole moments within each constituent Janus monolayer are identical, the vertical built-in electrostatic potential difference $Δϕ$ across the bilayer depends strongly on the orientations of these dipoles, which originates from the distinct interfacial configurations. As a consequence, the VSSe bilayers with different interfaces possess distinct interlayer magnetic couplings and show dramatically varied responses to external electric fields. For Se-S interface, reversible electric-field switching between antiferromagnetic (AFM) and ferromagnetic (FM) states can be achieved due to the competition between itinerant-electron-mediated FM exchange coupling and interlayer $Δϕ$-dependent AFM/FM super-superexchange interactions mediated by interfacial Se and S atoms. For Se-Se interface, both the valley polarization and spin splitting can be effectively reversed by the out-of-plane electric field, realizing an all-electric-field controlled anomalous valley Hall effect. Our results demonstrate that the interface of the magnetic Janus bilayer could act as an additional degree of freedom to tune the electronic, magnetic, and valley properties in 2D vdW materials. The Janus VSSe bilayers are identified as a promising platform for the design of low-power spintronic and valleytronic devices.

发表机构

• School of Physics, Hefei University of Technology（合肥工业大学物理学院）

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