Electrical reversal of the sign for magnon thermal Hall coefficient in a van der Waals bilayer antiferromagnet

With spin-layer locking, the manipulation of spin degree of freedom via perpendicular electric field can be realized in a typical antiferromagnetically coupled bilayer. In analogy to the electric control of the anomalous layer Hall effect of electron within such bilayer system, we propose here its magnon counterpart i.e., thermal Hall effect controlled by a perpendicular electric field. Unlike electrons, magnon is charged neutral and its transport in solids can be driven by a thermal gradient. It also exhibits Hall response due to the intrinsic Berry curvature of magnon, analogous to the achievement in electron system. Taking bilayer 2H-VSe2 with both H-type stacking and interlayer antiferromagnetic coupling as a platform, we perform first-principles calculations towards the magnetic exchange coupling parameters under applied electric field perpendicular to the plane. Based on linear spin wave approximation, we then fit the magnon band structures accordingly and calculate the corresponding Berry curvature. The thermal Hall coefficient dependence on the temperature under thermal gradient can be calculated correspondingly in linear response regime. It is shown that electric field reversal is able to reverse the sign of the coefficient. These findings provide a platform for the realization of all-electric magnon spintronics.