Tunable valley-selective circular polarization in vdW multilayers consisting of inversion-symmetric monolayers

Abstract

Valley manipulation via valley selective circular dichroism is beneficial for information encoding and processing. The fascinating scenarios arising from the coupling of valleys with other degrees of freedom bring us a new concept for valleytronics. In this work, we propose a design principle for the coupling of a valley with light polarization, a layer degree of freedom and electric polarization in van der Waals (vdW) multilayers consisting of inversion-symmetric monolayers. Taking ZrNBr multilayers as an example, we demonstrate that the valley selective dichroism properties can be regulated by switching the out-of-plane electric polarization via interlayer sliding. The intrinsic electric field induced by the electric polarization leads to the spatial separation of the photo-generated carriers under valley selective circular dichroism effects, which contributes to the valley Hall effect and the layer Hall effect. More interestingly, the spatial separation of carriers can be regulated by both interlayer sliding and light polarization. The coupling of multiple degrees of freedom demonstrated in this work is expected to have potential application in opto-valleytronics.