Tunable interlayer magnetism and band topology in van der Waals heterostructures of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Mn</mml:mi><mml:msub><mml:mi>Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>-family materials
Zhe Li, Jiaheng Li, Ke He, Xiangang Wan, Wenhui Duan, Yong Xu
Abstract
Manipulating interlayer magnetic coupling (IMC) of van der Waals (vdW) magnets is the key to tailoring material properties for various electronic applications and fundamental studies. Using $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$-family materials as examples, we systematically investigate the constituent-element dependence of IMC by first-principles calculations and attribute the IMC to unusual long-range superexchange interactions mediated by the $p$ orbitals across the vdW gap. Remarkably, a simple, universal rule is proposed to determine the sign of IMC (ferromagnetic or antiferromagnetic) by $d$-orbital occupation, and guidance is provided to achieve extraordinarily strong or stacking-dependent IMC by element engineering. Furthermore, several magnetic topological states are designed by heterostructuring, including ferromagnetic Weyl semimetals, high-order topological insulators, and unusual kinds of quantum anomalous Hall insulators. The findings enable us to engineer the magnetic and topological properties of $\mathrm{Mn}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$-family materials as well as other vdW magnetic materials and heterostructures.