Conductance and spin polarization for a quantum wire with the competition of Rashba and Dresselhaus spin–orbit coupling

Abstract

We investigate theoretically the spin transport of a quantum wire (QW) with weak Rashba and Dresselhaus spin–orbit coupling (SOC) nonadiabatically connected to two normal leads. Using scattering matrix method and Landauer–Büttiker formula within effective free-electron approximation, we have calculated spin-dependent conductances G ↑ and G ↓ , total conductance G and spin polarization P z for a hard-wall potential confined QW. It is demonstrated that, the SOCs induce the splitting of G ↑ and G ↓ and form spin polarization P z . Moreover, the conductances present quantized plateaus, the plateaus and P z show oscillation structures near the subband edges. Furthermore, with the increase of QW width a strong spin polarization ( P z ≈ 1 ) gradually becomes weak, which can be used to realize a spin filter. When the two SOCs coexist, the total conductance presents an isotropy transport due to the Rashba and Dresselhaus Hamiltonians being fixed, and the alteration of two SOCs strength ratio changes the sign of spin polarization. This may provide a way of realizing the expression of unit information by tuning gate voltage.