Yang Danxi, Fan Xiaoli, Zhang Fengxia, Hu Yan, Luo Zhifen
State Key Laboratory of Solidification Processing, Centre of Advanced Lubrication and Seal Materials, School of Material Science and Engineering, Northwestern Polytechnical University, 127 YouYi Western Road, Xi'an, 710072, Shannxi, China.
Nanoscale Res Lett. 2019 Jun 4;14(1):192. doi: 10.1186/s11671-019-3002-2.
By adopting the first-principle methods based on the density functional theory, we studied the structural, electronic, and magnetic properties of defected monolayer WSe with vacancies and the influences of external strain on the defected configurations. Our calculations show that the two W atom vacancies (V) and one W atom and its nearby three pairs of Se atom vacancies (V) both induce magnetism into monolayer WSe with magnetic moments of 2 and 6 μ, respectively. The magnetic moments are mainly contributed by the atoms around the vacancies. Particularly, monolayer WSe with V is half-metallic. Additionally, one Se and one W atom vacancies (V, V), two Se atom vacancies (V), and one W atom and the nearby three Se atoms on the same layer vacancy (V)-doped monolayer WSe remain as non-magnetic semiconducting. But the impure electronic states attributed from the W d and Se p orbitals around the vacancies locate around the Fermi level and narrow down the energy gaps. Meanwhile, our calculations indicate that the tensile strain of 0~7% not only manipulates the electronic properties of defected monolayer WSe with vacancies by narrowing down their energy gaps, but also controls the magnetic moments of V-, V-, and V-doped monolayer WSe.
通过采用基于密度泛函理论的第一性原理方法，我们研究了具有空位的缺陷单层WSe₂的结构、电子和磁性性质，以及外部应变对缺陷构型的影响。我们的计算表明，两个W原子空位（Vₗₗ）和一个W原子及其附近的三对Se原子空位（Vₗₗₗ）都能使单层WSe₂产生磁性，磁矩分别为2和6 μB。磁矩主要由空位周围的原子贡献。特别地，具有Vₗₗ的单层WSe₂是半金属的。此外，一个Se和一个W原子空位（Vₗ，Vₗₗ）、两个Se原子空位（Vₗₗ）以及一个W原子和同一层上附近的三个Se原子空位（Vₗₗₗ）掺杂的单层WSe₂仍为非磁性半导体。但是，空位周围W的d轨道和Se的p轨道产生的杂质电子态位于费米能级附近并缩小了能隙。同时，我们的计算表明，0~7%的拉伸应变不仅通过缩小能隙来操纵具有空位的缺陷单层WSe₂的电子性质，还能控制Vₗₗ、Vₗₗₗ和Vₗₗₗ掺杂的单层WSe₂的磁矩。
