Sliding- and twist-tunable valley polarization in bilayer NiI 2

作者：Linze Li, Li Xu, Liyan Lin, Dehe Zhang, Mingxing Chen, Di Wu, Yurong Yang · 发表于：Physical review. B./Physical review. B · 年份：2024 · DOI：10.1103/physrevb.110.205119 · 被引用次数：13 · 研究领域：2D Materials and Applications、MXene and MAX Phase Materials、Perovskite Materials and Applications

Valley, as an emerging degree of freedom of electron, has attracted extensive attention on account of its huge potential in electronic component technology. Two-dimensional (2D) materials provide an ideal platform for the research of valleytronics. Here, we study the sliding and twist effects on valley of bilayer ${\mathrm{NiI}}_{2}$ by the first-principles calculations. For a monolayer, spatial inversion symmetry maintains the degeneracy of two valleys. In the AA stacking bilayer, which can be obtained by a vertical translation operation on a monolayer structure, the valley band splitting is absent due to the $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{P}\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{T}$ joint symmetry. The interlayer sliding of the AA stacking bilayer can not break $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{P}\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{T}$ joint symmetry and therefore there is not valley band splitting in a sliding system with respect to AA stacking. For the ${\mathrm{AA}}^{\ensuremath{'}}$ stacking bilayer, the valley band splitting occurs while the valley polarization is still absent as the $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{{M}_{Z}}\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{T}$ joint symmetry. Different from the AA stacking system, $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{{M}_{Z}}\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{T}$ joint symmetry of the ${\mathrm{AA}}^{\ensuremath{'}}$ system can be broken by interlayer sliding, and the valley...