Transport Properties In A Gate Controlled Silicene Quantum Wire

Recently, the research of Silicene has become focus in the field of condensed matter physics. Silicene is a two-dimensional honeycomb lattice formed by a monolayer of silicon atoms, which has similar electrical properties to those of graphene. Silicene attracts much attention due to it has a relatively large spin-orbit coupling. Through a lot of experiments and theory study, we see the silicene material is a new two-dimensional topological insulator. These novel physical properties of silicene material both for the future in the industrial application and for fundamental physics research have very important significance, so the silicene material is expected to be the next research focus in the low dimensional system.The transport properties through a silicene quantum wire controlled by a gate are studied by using the non-equilibrium Green function formalism. A pair of gapless and spin-polarized edge states appears only when the gate voltage is strong and the silicene quantum wire has perfect zigzag or armchair boundaries in which additional silicon atoms are absent. Moreover, the edge states controlled by gate are spin valley-polarized, that is the direction of spin is opposite in different valley, which is different from that of the edge states at the interfaces between the silicene and vacuum. These results can be helpful to design and fabricate the practical silicene nanostructure.The first chapter we mainly introduced the emergence and development status of silicene material and the positive influence of the industrial development in the future. The silicene crystal structure, electrical and spin transport properties are introduced in detail, which make readers understanding of silicene material simple.The second chapter, we mainly introduced the Green's function method in the transport theory of the mesoscopic system and the Green's function is derived. As long as we know that the whole system of the Green's function can be obtained, the related physical quantities of the system can be calculated.The third chapter, we mainly introduced the transport properties in a gate controlled silicene quantum wire. A pair of gapless and spin-polarized edge states appears only when the gate voltage is strong and the silicene quantum wire has perfect zigzag or armchair boundaries in which additional silicon atoms are absent. These results can be helpful to design and fabricate the practical silicene nanostructure.