凝聚态物理
点反射
原子轨道
拓扑序
相变
半金属
半导体
单层
几何相位
物理
带隙
材料科学
量子
电子
量子力学
纳米技术
作者
Wenzhe Zhou,Guibo Zheng,Zhenzhen Wan,Tingyu Sun,Aolin Li,Fangping Ouyang
摘要
Due to the breaking of the time reversal symmetry and spatial inversion symmetry, hexagonal ferrovalley materials have intrinsic large valley polarization. Model analysis shows that tuning the two different band gaps of valleys can realize phase transitions between ferrovalley semiconductors, half valley metals, and valley-polarized quantum anomalous Hall semiconductors. Through first-principle calculations, monolayer ferrovalley materials RuXY (X, Y = F, Cl, Br), which exhibit valley splitting at the top valence band and the bottom conduction band, are predicted to achieve this valley-dependent topological phase transition. Due to the different orbital proportions of d orbitals, the valley splitting at the top valence band is much greater than that at the bottom conduction band. Strain can regulate the interaction between orbitals, thus producing valley-dependent band inversion, leading to the quantum spin or valley Hall effect. The chiral edge states are demonstrated under appropriate biaxial strain. The topological phase transition is related to the inversion of the band structure and Berry curvatures at K and K′ valleys. These results have certain significance for the design of two-dimensional valley-dependent quantum materials and the application of valleytronic devices.
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