School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
Nanoscale. 2019 Mar 21;11(12):5666-5673. doi: 10.1039/c9nr00826h.
Recent experimental success in the realization of two-dimensional (2D) magnetism has invigorated the search for new 2D magnetic materials with a large magnetocrystalline anisotropy, high Curie temperature, and high carrier mobility. Using first-principles calculations, here we predict a novel class of single-spin Dirac fermion states in a 2D Ta2S3 monolayer, characterized by a band structure with a large gap in one spin channel and a Dirac cone in the other with carrier mobility comparable to that of graphene. Ta2S3 is dynamically and thermodynamically stable under ambient conditions, and possesses a large out-of-plane magnetic anisotropy energy and a high Curie temperature (TC = 445 K) predicted from the spin-wave theory. When the spin and orbital degrees of freedom are allowed to couple, the Ta2S3 monolayer becomes a Chern insulator with a fully spin-polarized half-metallic edge state. An effective four-band tight-binding model is constructed to clarify the origin of a semi-Dirac cone in a spin-up channel and nontrivial band topology, which can be well maintained on a semiconducting substrate. The combination of these unique single-spin Dirac fermion and quantum anomalous Hall states renders the 2D Ta2S3 lattice a promising platform for applications in topologically high fidelity data storage and energy-efficient spintronic devices.
最近在实现二维（2D）磁性方面的实验成功，激发了人们对具有大磁各向异性、高居里温度和高载流子迁移率的新型 2D 磁性材料的探索。在这里，我们使用第一性原理计算预测了一种新型单层 Ta2S3 中的单自旋狄拉克费米子态，其能带结构在一个自旋通道中具有大带隙，而在另一个自旋通道中具有载流子迁移率可与石墨烯媲美的狄拉克锥。Ta2S3 在环境条件下是动力学和热力学稳定的，并且具有大的面外磁各向异性能和高的居里温度（TC = 445 K），这是从自旋波理论预测的。当允许自旋和轨道自由度耦合时，Ta2S3 单层成为具有完全自旋极化的半金属边缘态的 Chern 绝缘体。构建了有效的四能带紧束缚模型，以阐明在自旋向上通道中半狄拉克锥和非平凡能带拓扑的起源，这在半导体衬底上可以很好地保持。这些独特的单自旋狄拉克费米子和量子反常霍尔态的结合，使得 2D Ta2S3 晶格成为拓扑高保真数据存储和节能自旋电子器件应用的有前途的平台。
