磁性硅烯超晶格中电场调制的谷极化和自旋极化  

Valley and spin polarization manipulated by electric field in magnetic silicene superlattice

作　　者：侯海燕 姚慧 李志坚[1,2] 聂一行 Hou Hai-Yan;Yao Hui;Li Zhi-Jian;Nie Yi-Hang(State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Theoretical Physics Shanxi University, Taiyuan 030006, China;Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China)

机构地区：[1]山西大学理论物理研究所,量子光学与光量子器件国家重点实验室,太原030006 [2]山西大学极端光学协同创新中心,太原030006

出　　处：《物理学报》2018年第8期176-184,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号：11274208); 山西省“1331”工程(批准号：201542030)资助的课题

摘　　要：研究了基于硅烯的静电势超晶格、铁磁超晶格、反铁磁超晶格中谷极化、自旋极化以及赝自旋极化的输运性质,分析了铁磁交换场、反铁磁交换场以及化学势对输运性质的影响,讨论了电场对谷极化、自旋极化以及赝自旋极化的调控作用.结果表明:当3种超晶格的晶格数达到10以上时,在硅烯超晶格中很容易实现100%的谷极化、自旋极化和赝自旋极化,而且通过调节超晶格上的外加电场可以使极化方向发生翻转,从而在硅烯超晶格中实现外电场对谷自由度、自旋自由度以及赝自旋自由度的操控.Silicene is a close relative of graphene with a honeycomb lattice structure. However, silicene is unlike the strictly two-dimensional graphene and it has a buckled structure, i.e., the A and B atoms form two sublattice planes with a small vertical separation distance in between. Thus a perpendicular electric field applied to silicene can induce a staggered sublattice potential and different onsite energies in the A and B sublattices. As a result, silicene has a large spin-orbit gap compared with graphene. In addition, the mass of Dirac electrons in silicone is controllable by an external electric field, which leads to several controllable polarized transports in the silicene junction, including valley-, spinand pseudospin-polarization transport. However, in a single silicone junction the manipulations of polarizations are not ideal. In this work, we consider several silicene-based superlattices in order to effectively control the properties of polarization transport. Using the transfer matrix method, we study valley-, spin-and pseudospin-polarization transport in silicene-based electrostatic potential, ferromagnetic and antiferromagnetic superlattices. The effects of ferromagnetic exchange field, antiferromagnetic exchange field and chemical potential on transport properties are analyzed and the roles of electrostatic field in regulating valley-, spin-and pseudospin-polarization are discussed. The ferromagnetic superlattices result in spin-dependent chemical potential in ferromagnetic regime, while Dirac-like mass depends on the antiferromagnetic exchange field and spin. For electrostatic potential superlattice, the pseudospin-polarization occurs and there is no spin-polarixation nor valley-polarization. The peaks of both the pseudospin conductances are completely separated from each other and the pseudospin is completely polarized in the wide range of the zero field for both sides.For ferromagnetic superlattice, the ferromagnetic exchange field and chemical potential lead to the concurrences of spinand valley-po

关 键 词：硅烯超晶格 电场调制 谷极化 自旋极化 

分 类 号：O469[理学—凝聚态物理]