All-electrical generation of spin-polarized currents in quantum spin Hall insulators

摘要

The control and generation of spin-polarized current (SPC)without magnetic materials and an external magneticfield is a big challenge in spintronics and normally requires a spin-flip mechanism. In this Rapid Communication,we show the theoretical discovery of all-electrical generation of SPC without relying on spin-flip spin-orbitcoupling (SOC).We find that the SPC can be produced as long as an energy-dependent phase difference betweenthe spin up and down electrons can be established. We verify this through quantum transport calculations on agated stanene zigzag nanoribbon, which is a quantum spin Hall (QSH) insulator. Our calculations indicate that thetransient current as well as ac conductance are significantly spin polarized, which results from the genetic phasedifference between spin up and down electrons after traversing the system. Our results are robust against edgeimperfections and generally valid for other QSH insulators, such as silicene and germanene, etc. These findingsestablish a different route for generating SPCs by purely electrical means and open the door for interestingapplications of semiconductor spintronics.