局域交换场和电场调控的锗烯纳米带自旋过滤效应  

Spin filter effect of germanene nanoribbon controlled by local exchange field and electric field

作　　者：相阳 郑军 李春雷[2] 郭永[3,4] Xiang Yang;Zheng Jun;Li Chun -Lei;Guo Yong(College of Mathematics and Physics, Bohai University, Jinzhou 121013, China;College of Elementary Education, Capital Normal University, Beijing 100048, China;Department of Physics, Tsinghua University, Beijing 100084, China;Collaborative Innovation Center of Quantum Matter, Beijing 100084, China)

机构地区：[1]渤海大学数理学院,锦州121013 [2]首都师范大学初等教育学院,北京100048 [3]清华大学物理系,北京100084 [4]量子物质科学协同创新中心,北京100084

出　　处：《物理学报》2019年第18期268-273,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11604021,11574173);低维量子物理国家重点实验室开放课题(批准号:KF201806);北京市教育委员会科技计划一般项目(批准号:KM201810028022)资助的课题~~

摘　　要：基于非平衡格林函数方法,理论研究了Z轴方向局域交换场和电场对锗烯纳米带中电子自旋极化输运性质的影响.结果表明对锗烯的边缘区域施加强度大于其2倍有效自旋轨道耦合强度的交换场,可使自旋向上和向下电子的能带在不同的能量区间产生带隙,从而实现对不同自旋取向电子的100%过滤.提出了一种利用电场辅助降低自旋过滤效应所需阈值交换场强度的方法.研究表明,同时对中心器件区域施加局域交换场和电场,可以在小于有效自旋轨道耦合的弱交换场强度下,在较大的能量窗口区域过滤自旋向上或向下的电子.增大局域交换场强度,自旋过滤效应所对应的能量区间显著增大.Germanene, which has been synthesized recently, is a single-layered material composed of germanium atoms. Almost all the striking properties of graphene can be transferred to germanene, because both of them have the same honeycomb lattice structure. In contrast with graphene, germanene has a sizable band gap and spin dependent helical edge states, which make it attractive candidate for spintronic applications. By using the nonequilibrium Green’ s function method, the effects of Z-axis local exchange field and electric field on spinpolarized transport properties in germanene nanoribbon are studied theoretically. The results reveal that by exerting an exchange field with a strength greater than twice the effective spin-orbit coupling to the edge region of germanene, the spin resolved band gaps can be generated in different energy ranges, and thus 100% filtering of spin-up or spin-down electrons can be achieved. We theoretically propose a method to reduce the threshold exchange field strength for the spin filter effect by using the electric field. The results show that the spin-filter effect can be achieved in a larger energy range under a weaker exchange field when the electric field are applied to the entire central device region. With the increase of the local exchange field intensity, the energy range corresponding to the spin filter effect will increase significantly.

关 键 词：锗烯 局域交换场 自旋过滤效应 

分 类 号：TB383.1[一般工业技术—材料科学与工程] TQ134.31[化学工程—无机化工]