二维过渡金属硫化物中Rashba自旋轨道耦合效应的电场调控研究  

Electrical manipulation of Rashba spin-orbit coupling in the two-dimensional transition metal dichalcogenide

作　　者：姚群芳 蔡佳[1] 龚士静[1] 

机构地区：[1]华东师范大学极化材料与器件教育部重点实验室,上海200241

出　　处：《华东师范大学学报（自然科学版）》2018年第2期101-108,共8页Journal of East China Normal University(Natural Science)

基　　金：上海市自然科学基金(14ZR1412700);国家自然科学基金(61774059)

摘　　要：本文采用基于密度泛函理论的第一性原理计算方法,对6种二维过渡金属硫化物MX_2(M=Mo,W;X=S,Se,Te)中的Rashba自旋轨道耦合效应进行了系统研究.对6种MX_2材料施加垂直方向电场,发现阴离子X对于电场诱导的Rashba自旋轨道耦合效应起主要作用:X原子序数越大,电场诱导的Rashba劈裂也越大;阳离子M被阴离子X覆盖,对电场诱导的Rashba自旋劈裂影响较弱.因此,6种MX_2单层的Rashba自旋劈裂大小依次为:WTe_2>MoTe_2>WSe_2>MoSe_2>WS_2>MoS_2.施加电场后,从布里渊区中心Γ点到布里渊区边界K/K′点,自旋方向二维平面内转向垂直方向,并且随着电场的增加,面内自旋成分逐渐增加.Using the first-principles density functional theory calculations, we investigate the Rashba spin-orbit coupling of the transition metal dichalcogenide(TMD) monolayers MX_2(M=Mo, W; X =S, Se, Te) induced by the external electric field. It is found that the anions X play an important role on the Rashba spin-orbit coupling effect. With the increase of the atomic number of X, Rashba spin-orbit splitting around the Γ point increases more distinctively, and the external electric field can hardly influence the cations because of the coverage by the anions. Thus the strength of the Rashba spin-orbit coupling follows the sequence: WTe_2 >MoTe_2 >WSe_2 >MoSe_2 >WS_2 >MoS_2. Furthermore, the distribution of the spin polarization along the high symmetry line Γ-K/K' turns from the vertical direction to the two-dimensional plane under the external electric fields, and the in-plane spin polarization distribution rises with the increase of the external electric field.

关 键 词：二维过渡金属硫化物 RASHBA自旋轨道耦合 第-性原理计算 

分 类 号：O411.3[理学—理论物理]