Angeli Mattia, MacDonald Allan H
International School for Advanced Studies, I-34136 Trieste, Italy;
Physics Department, University of Texas at Austin, Austin, TX 78712
Proc Natl Acad Sci U S A. 2021 Mar 9;118(10). doi: 10.1073/pnas.2021826118.
The valence band maxima of most group VI transition metal dichalcogenide thin films remain at the Γ point all of the way from bulk to bilayer. In this paper, we develop a continuum theory of the moiré minibands that are formed in the valence bands of Γ-valley homobilayers by a small relative twist. Our effective theory is benchmarked against large-scale ab initio electronic structure calculations that account for lattice relaxation. As a consequence of an emergent [Formula: see text] symmetry, we find that low-energy Γ-valley moiré holes differ qualitatively from their K-valley counterparts addressed previously; in energetic order, the first three bands realize 1) a single-orbital model on a honeycomb lattice, 2) a two-orbital model on a honeycomb lattice, and 3) a single-orbital model on a kagome lattice.
大多数 VI 族过渡金属二硫属化物薄膜的价带最大值从体相到双层始终位于 Γ 点。在本文中,我们发展了一种连续介质理论,用于研究由小相对扭转在 Γ 谷同质双层价带中形成的莫尔微带。我们的有效理论以考虑晶格弛豫的大规模从头算电子结构计算为基准。由于出现的[公式:见原文]对称性,我们发现低能 Γ 谷莫尔空穴在性质上不同于先前研究的 K 谷对应物;按能量顺序,前三个能带分别实现 1) 蜂窝晶格上的单轨道模型,2) 蜂窝晶格上的双轨道模型,以及 3) kagome 晶格上的单轨道模型。