磁性掺杂三维拓扑绝缘体的自旋相关光电流研究  

Investigation on spin dependent photocurrent of magnetically doped three-dimensional topological insulators

作　　者：潘庆高 王雨濛 俞金玲[1] PAN Qinggao;WANG Yumeng;YU Jinling(College of Physics and Information Engineering,Fuzhou University,Fuzhou,Fujian 350108,China)

机构地区：[1]福州大学物理与信息工程学院,福建福州350108

出　　处：《福州大学学报（自然科学版）》2022年第2期187-191,共5页Journal of Fuzhou University(Natural Science Edition)

基　　金：国家自然科学基金资助项目(62074036,61674038);福建省对外合作资助项目(2019I0005);福建省高校杰出青年科研计划资助项目(00382408)。

摘　　要：通过圆偏振光致电流及反常圆偏振光致电流的光学实验方法,研究磁性掺杂对三维拓扑绝缘体的影响.在圆偏振光激发下,相对于未掺杂三维拓扑绝缘体Bi_(2)Te_(3),其光电流方向不变,但幅值有所减小.这是由于磁性掺杂使得三维拓扑绝缘体狄拉克能带带隙打开,相同激发条件下,带间激发概率降低,光生自旋极化载流子浓度降低.对其光电导信号的分析则进一步表明,磁性掺杂使得拓扑绝缘体对激发光的吸收大大降低,进而限制了光电流的产生.此外,磁性掺杂三维拓扑绝缘体所产生的反常圆偏振光致电流随着发光位置发生了三次反向,这是由于磁性掺杂三维拓扑绝缘体的上下表面态分别贡献了方向相反的光电流,通过拟合,分离了上下表面态各自的贡献.The effect of magnetic doping on three-dimensional topological insulators is studied by optical experiments of circularly polarized and anomalously circularly polarized optical currents.Under the excitation of circularly polarized light,the photocurrent direction of Bi_(2)Te_(3) is unchanged,but its amplitude decreases.This is because the magnetic doping opens the Dirac band gap of the three-dimensional topological insulator.Under the same excitation condition,the inter-band excitation probability decreases and the concentration of photogenerated spin polarized carriers decreases.The analysis of the photoconductance signal further shows that magnetic doping greatly reduces the absorption of excited light and thus restricts the generation of photocurrent.In addition,the anomalous circularly polarized light flow generated by the magnetically doped 3D topological insulator reverses three times with the position of excitation light,because the upper and lower surface states of the magnetically doped 3D topological insulator contribute opposite photocurrents respectively.By fitting,the contributions of the upper and lower surface states are separat.

关 键 词：磁性掺杂三维拓扑绝缘体 圆偏振光致电流 反常圆偏振光致电流 表面态 

分 类 号：O472.1[理学—半导体物理]