Ferroelectric control of magnetic coupling of monolayer MnBr2 in semiconducting multiferroic van der Waals heterostructure

Multiferroic van der Waals (vdW) heterostructures composed of vdW intrinsic magnets and ferroelectrics hold great significance in energy-efficient vdW spintronic devices. In this work, using first-principles calculations, we investigate the electronic structure and magnetic properties of monolayer MnBr2 as well as the electronic structure and magnetoelectric coupling properties of vdW heterostructure formed by sandwiching antiferromagnetic (AFM) monolayer MnBr2 between two intrinsically ferroelectric monolayer α-In2Se3 (In2Se3/MnBr2/In2Se3 vdW heterostructure). It is found that the ground state of monolayer MnBr2 is AFM state and the magnetic structure is ferromagnetic (FM) stripes of width two atom rows within the layer with AFM coupling between neighboring stripes, in which the AFM and FM couplings originate from superexchange interaction mediated by the pσ and pπ orbitals of the intervening Br in Anderson’s mechanism, respectively. Intriguingly, the ground state of the sandwiched monolayer MnBr2 in the In2Se3/MnBr2/In2Se3 vdW heterostructure can be reversibly switched between AFM and FM states by electrically reversing the ferroelectric polarization direction of α-In2Se3 and the In2Se3/MnBr2/In2Se3 vdW heterostructures are semiconducting for all polarized configurations. Our results present new opportunities for exploring energy-efficient vdW spintronic devices based on semiconducting multiferroic vdW heterostructures.