Spin-dependent electron transport in a Rashba quantum wire with rough edges

TL;DR

This paper theoretically studies how rough edges in a Rashba quantum wire affect spin-dependent electron transport, revealing that edge disorder destroys charge conductance quantization but can generate and manipulate spin conductance, with implications for spintronics.

Contribution

It introduces a detailed theoretical analysis of spin-dependent transport in disordered Rashba wires, highlighting the effects of edge roughness and magnetic fields on conductance properties.

Findings

Edge disorder destroys charge conductance quantization.

Nonzero spin conductance can be generated and controlled.

Magnetic fields can mitigate edge roughness effects.

Abstract

We investigate theoretically the spin-dependent electron transport in a Rashba quantum wire with rough edges. The charge and spin conductances are calculated as function of the electron energy or the wire length by adopting the spinresolved lattice Green function method. For a single disordered Rashba wire, it is found that the charge conductance quantization is destroyed by the edge disorder. However, a nonzero spin conductance can be generated and its amplitude can be manipulated by the wire length, which is attributed to the broken structure symmetries and the spin-dependent quantum interference induced by the rough boundaries. For a large ensemble of disordered Rashba wires, the average charge conductance decreases monotonically, however, the average spin conductance increases to a maximum value and then decreases, with increasing wire length. Further study shows that the influence of the rough edges on the charge and spin conductances can be eliminated by applying a perpendicular magnetic field to the wire. In addition, a very large magnitude of the spin conductance can be achieved when the electron energy lies between the two thresholds of each pair of subbands. These findings may not only benefit to further apprehend the transport properties of the Rashba low-dimensional systems but also provide some theoretical instructions to the application of spintronics devices.