Spin transport for a quantum wire with coexistence of Rashba and Dresselhaus spin-orbit coupling in quantum wire and two leads

Abstract

We theoretically investigate the spin-dependent conductance, the total conductance and the spin polarization of a quantum wire with the coexistence of Rashba and Dresselhaus spin-orbit coupling in the quantum wire and two leads, respectively. First, we find that the Rashba or Dresselhaus spin-orbit coupling in the quantum wire induces the split of spin-dependent conductance and forms the out-of-plane spin polarization. Moreover, when Rashba strength or Dresselhaus strength in the quantum wire increases, the split of conductance is enlarged and the intensity of spin polarization is enhanced accordingly. Furthermore, when two spin-orbit couplings coexist in the quantum wire and two leads, the addition of spin-orbit coupling in two leads expands the oscillation ranges of conductance plateaus and spin polarization, respectively, and further strengthens the magnitude of spin polarization. In particular, when the Rashba coupling in two leads exists and the quantum wire is wide, the total conductance jumps to upper conductance plateaus and the direction of spin polarization changes, while for the Dresselhaus coupling no such results exist. Our calculations indicate that one can realize the modulation of the strength and direction of spin polarization by altering the width of wire, the Rashba or Dresselhaus strength in quantum wire, the Rashba or Dresselhaus strength in two leads, respectively, which may be used to design the spin filter.