论文标题
单层Mosi $ _ {2} $ n $ _ {4} $，wsi $ _ {2} $ n $ _ {4} $和mosi $ _ {2} $ as $ _ {4} $
Valley-dependent properties of monolayer MoSi$_{2}$N$_{4}$, WSi$_{2}$N$_{4}$ and MoSi$_{2}$As$_{4}$
论文作者
论文摘要
在最近的一项工作，新的二维材料中，单层mosi $ _ {2} $ n $ _ {4} $和wsi $ _ {2} $ _ {4 $ _ {4} $，在实验中已成功合成，以及其他几种单层材料，以及类似结构，例如$ $ _} $ _} $ _} $ _ {2} [{\ color {blue} Science 369，670-674（2020）}]。在这里，基于第一原则计算和理论分析，我们研究了单层Mosi $ _ {2} $ n $ _ {4} $，WSI $ _ {2} $ n $ n $ _ {4} $ _ {4} $ _ {4} $ and Mosi $ _ {2} $ as $ _ aS $ _ {4} $。我们表明这些材料是半导体，一对二十型型山谷位于六角形布里渊区的角落。由于反转对称性和自旋轨道耦合的影响，山谷费米子表现出旋转 - 瓦利耦合，山谷对抗性的浆果曲率和山谷选择性的光学圆形二色性。我们还为山谷构建了低能的有效模型，计算自旋霍尔电导率和介电常数，并研究对带结构的应变效应。我们的结果揭示了单层Mosi $ _ {2} $ n $ _ {4} $，WSI $ _ {2} $ _ {2} $ n $ _ {4} $和MOSI $ _ {2} $作为$ _ {4} $的有趣的谷物理学。
In a recent work, new two-dimensional materials, the monolayer MoSi$_{2}$N$_{4}$ and WSi$_{2}$N$_{4}$, have been successfully synthesized in experiment, and several other monolayer materials with the similar structure, such as MoSi$_{2}$As$_{4}$, have been predicted [{\color{blue}Science 369, 670-674 (2020)}]. Here, based on first-principles calculations and theoretical analysis, we investigate the electronic and optical properties of monolayer MoSi$_{2}$N$_{4}$, WSi$_{2}$N$_{4}$ and MoSi$_{2}$As$_{4}$. We show that these materials are semiconductors, with a pair of Dirac-type valleys located at the corners of the hexagonal Brillouin zone. Due to the broken inversion symmetry and the effect of spin-orbit coupling, the valley fermions manifest spin-valley coupling, valley-contrasting Berry curvature, and valley-selective optical circular dichroism. We also construct the low-energy effective model for the valleys, calculate the spin Hall conductivity and the permittivity, and investigate the strain effect on the band structure. Our result reveals interesting valley physics in monolayer MoSi$_{2}$N$_{4}$, WSi$_{2}$N$_{4}$ and MoSi$_{2}$As$_{4}$, suggesting their great potential for valleytronics and spintronics applications.
