PT-Symmetry Breaking and Spin Control in 2D Antiferromagnetic MnSe.

Two-dimensional (2D) materials with intrinsic antiferromagnetic (AFM) order provide a unique avenue to harness both charge and spin degrees of freedom for practical spintronics applications. Here, by using ab initio electronic structure calculations, the interplay of discrete crystal symmetries (such as inversion (P ), time-reversal (T ), or combined PT symmetry) of 2D semiconducting AFM manganese selenide (MnSe) and external electric field along with graphene proximity is investigated. We show that both an external electric field and graphene proximity can independently break otherwise conserved combined PT symmetry in 2D MnSe, resulting in large and tunable spin-splittings in both valence and conduction bands, and provide electrical control over a wide energy range. We further propose a current-in-plane electronic device consisting of semiconducting 2D MnSe as a channel material and graphene as a metal contact which preserves not only these features but additionally provides a mechanism to further tune metal-semiconductor contact characteristics such as Schottky barrier height leading to an Ohmic contact. Our results provide a comprehensive insight into the electrical control of the charge and spin degrees of freedom in 2D AFM MnSe.