Spin current between the two different topological phases in the equilibrium system

Abstract

In this paper, we analyze the equilibrium spin current in a two-dimensional electron gas with a Rashba spin–orbit coupling at zero bias. Silicene has been successfully synthesized on a two-dimensional honeycomb lattice, and has some unique features due to its buckled structure. By applying the electric and exchange fields, various phases can be realized, such as valley polarized metal (VPM) phase, quantum anomalous Hall state and quantum spin Hall (QSH) state. Both VPM and QSH exhibit metalliclike behavior, we put two different phases in an infinite zigzag nanoribbon, even the weak inhomogeneity of the Rashba medium leads to spin current, and introduce how to control the output polarized current by tuning the electric and exchange fields. Furthermore, we define the concept of bond spin current, and plot the spatial distribution of microscopic spin current. In particular, spin vortex appears when the injected energy is close to the Fermi level, where spin current changes most violently.

Keywords

• Rashba spin–orbit (SO) coupling inhomogeneity
• bond spin current
• spin vortex
• silicene