过渡金属原子X(X=Mn、Fe、Co)掺杂单层Janus WSSe的第一性原理研究

First-principles study on the transition metal atoms X(X=Mn,Fe,Co)doped Janus WSSe monolayer

二维Janus WSSe作为一种新兴的过渡金属硫族化合物(TMDs)材料,由于其打破了面外镜像对称性,且具有内在垂直压电和强Rashba自旋轨道耦合效应等丰富的物理特性,在自旋电子器件中具有巨大的应用潜力。本文基于密度泛函理论的第一性原理平面波赝势方法计算了过渡金属原子X(X=Mn、Fe、Co)掺杂单层Janus WSSe的电子结构、磁性和光学性质。结果表明:在Chalcogen-rich(硫族元素为多数元素)条件下的掺杂比在W-rich(钨元素为多数元素)条件下的掺杂展现出更高的稳定性,且掺杂后所有体系均表现出磁性。值得一提的是,对该体系进行Mn掺杂后,自旋向上通道出现杂质能级,WSSe由原来的非磁性半导体转变成磁矩为1.043μ_(B)的铁磁性半金属。而Fe、Co的掺杂使得自旋向上通道和自旋向下通道均出现杂质能级,呈现出磁矩分别为1.584μ_(B)、2.739μ_(B)的金属性。此外,掺杂体系的静态介电常数都显著增加,极化程度增强,且介电函数虚部和光吸收峰都发生了红移,说明掺杂有利于对可见光的吸收。

Two-dimensional(2D)Janus WSSe,as an emerging transition metal dichalcogenides(TMDs)material,breaks the out-of-plane mirror symmetry and possesses abundant physical properties such as intrinsic vertical piezoelectricity and strong Rashba spin-orbit coupling effect,which has great application potential in spintronic devices.In this paper,the electronic structures,magnetic and optical properties of the Janus WSSe monolayer doped with transition metal atoms X(X=Mn,Fe,Co)were calculated using the first-principles plane wave method based on density functional theory.The results show that doping under Chalcogen-rich(chalcogen element is the majority element)condition exhibits higher stability than under W-rich(tungsten element is the majority element)condition,and all systems exhibit magnetic properties after doping.After Mn doping,the impurity levels appear in the spin-up channel,which changes the WSSe system from a non-magnetic semiconductor to a ferromagnetic semi-metal with a magnetic moment of 1.043μ_(B).After Fe and Co doping,the impurity levels appear in both the spin-up and spin-down channels,making the Fe and Co-doped systems exhibit a metallic nature with magnetic moments of 1.584μ_(B)and 2.739μ_(B),respectively.In addition,the static dielectric constant of the doped system is significantly increased,the polarization degree is enhanced,and both the imaginary part of the dielectric function and the optical absorption peak are red-shifted,indicating that doping is beneficial to the absorption of visible light.