圆偏振光场调控的锡烯纳米带热自旋输运  

Circularly-polarized light controlled thermal spin transport in stanene nanoribbon

作　　者：相阳 郑军[1,2] 李春雷[3] 王小明[4] 袁瑞旸[5] Xiang Yang;Zheng Jun;Li Chun-Lei;Wang Xiao-Ming;Yuan Rui-Yang(College of Physics Science and Technology,Bohai University,Jinzhou 121013,China;State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China;College of Elementary Education,Capital Normal University,Beijing 100048,China;Middle School Affiliated to China University of Geosciences,Beijing 100083,China;Department of Physics,Capital Normal University,Beijing 100048,China)

机构地区：[1]渤海大学物理科学与技术学院,锦州121013 [2]清华大学物理系,低维量子物理国家重点实验室,北京100084 [3]首都师范大学初等教育学院,北京100048 [4]中国地质大学附属中学,北京100083 [5]首都师范大学物理系,北京100048

出　　处：《物理学报》2021年第14期275-281,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11604021);辽宁省“兴辽英才”青年拔尖人才项目(批准号:XLYC20);辽宁省自然科学基金计划指导项目(批准号:2019-ZD-0501);辽宁省教育厅青年科技人才“育苗”项目(批准号:LQ2019015);北京市教育委员会科技计划面上项目(批准号:KM201810028022);低维量子物理国家重点实验室开放课题(批准号:KF201910)资助的课题.

摘　　要：利用非平衡格林函数方法理论研究了光场和电场对锡烯纳米带自旋相关热电效应的影响.研究表明,热电电流的性质和强度可以通过圆偏振光场的强度和偏振化方向进行有效调控.在较强的左旋圆偏振光场和电场的共同作用下,锡烯自旋向下的边缘态发生相变形成带隙,通过温度梯度的驱动可以获得100%极化的自旋向下的自旋流.当施加右旋偏振光时,自旋向上的边缘态被破坏,可以产生完全极化的自旋向上的热自旋流.在较弱的外场作用下,边缘态的性质不发生改变,系统不对外输出热电电流.此外,研究表明热自旋流的大小与带隙的宽度有关,适度地增加温度可以显著增大热自旋流的峰值,但是较高的平衡温度和温度梯度将抑制自旋热电效应.The major challenge of spintronics lies in how to generate,manipulate,and detect spin current.Multiple methods,such as using magnetic materials,magnetic field,and polarized light field to manipulate the spin of electrons,have been proposed.Owing to the possible applications in spintronic devices,there is currently great interest in the field of spin caloritronics,which focuses on the interplay of spin and heat currents.Stanene is a type of two-dimensional topological insulator consisting of a single layer of Sn atoms arranged in a hexagonal lattice.In this paper,the effects of light and electric fields on the spin-dependent thermoelectric effect of the stanene nanoribbon are studied theoretically based on the non-equilibrium Green’s function method.The results show that the properties and intensity of the thermoelectric current can be effectively controlled by the intensity and the polarization direction of the circularly polarized light field.Under the joint action of a strong circularly-polarized light field and an electric field,the stanene can transform from a quantum spin-Hall insulator into a spin-polarized quantum Hall insulator.When the left-circularly-polarized light field is applied,the spin-down edge states of stanene undergo a phase transition to form a bandgap,and a 100%spin-polarized spin-down current driven by temperature gradient can be obtained.When the right-circularly-polarized light is applied,the edge states of spin-up electrons are destroyed,and a completely polarized spin-up thermal current can be generated.In the weak external field,the properties of the edge state do not change,and the system does not output a thermoelectric current.In addition,the study shows that the intensity of the thermal spin current is related to the width of the bandgap,and a moderate increase in temperature can significantly increase the peak value of the current,but the higher equilibrium temperature and temperature gradient will restrain the spin thermoelectric effect.

关 键 词：自旋相关热电效应 圆偏振光场 锡烯 

分 类 号：O469[理学—凝聚态物理]