Valley physics in tin (II) sulfide

Tin (II) sulfide (SnS) is a layered mineral found in nature. In this paper, we study the two-dimensional (2D) form of this material using a combination of ab initio calculation and k . p theory. In particular, we address the valley properties and the optical selection rules of 2D SnS. Our study reveals SnS as an extraordinary material, where there are two pairs of valleys, each placed along the two perpendicular axes, which can be selected exclusively with linearly polarized light, and can be separated using nonlocal electrical measurements.