We introduce the concept of valley-layer coupling (VLC) in two-dimensional materials, where the low-energy electronic states in the emergent valleys have valley-contrasted layer polarization such that each state is spatially localized on the top or bottom super-layer. The VLC enables a direct coupling between valley and gate electric field, opening a new route towards electrically controlled valleytronics. We analyze the symmetry requirements for the system to host VLC, demonstrate our idea via first-principles calculations and model analysis of a concrete 2D material example, and show that an electric, continuous, wide-range, and switchable control of valley polarization can be achieved by VLC. Furthermore, we find that systems with VLC can exhibit other interesting physics, such as valley-contrasting linear dichroism and optical selection of the electric polarization of interlayer excitons.
Cite
@article{arxiv.1904.06498,
title = {Valley-Layer Coupling: A New Design Principle for Valleytronics},
author = {Zhi-Ming Yu and Shan Guan and Xian-Lei Sheng and Weibo Gao and Shengyuan A. Yang},
journal= {arXiv preprint arXiv:1904.06498},
year = {2020}
}