Spin Hall effect in clean two dimensional electron gases with Rashba spin-orbit coupling

TL;DR

This paper investigates how current flow induces spin polarization in clean 2D electron gases with Rashba spin-orbit coupling, revealing geometry-dependent effects and potential for enhancement.

Contribution

It provides a detailed analysis of edge-induced spin polarization effects in different geometries of 2D electron gases with Rashba coupling, highlighting conditions for enhancement.

Findings

Spin polarization peaks at low energies near the band bottom in wide samples.

Evanescent modes contribute significantly to out-of-plane spin components.

Interference effects dominate spin polarization in quantum wires, sensitive to Fermi energy.

Abstract

We study the spin polarization induced by a current flow in clean two dimensional electron gases with Rashba spin-orbit coupling. This geometric effect originates from special properties of the electron's scattering at the edges of the sample. In wide samples, the spin polarization has it largest value at low energies (close to the bottom of the band) and goes to zero at higher energies. In this case, the spin polarization is dominated by the presence of evanescent modes which have an explicit spin component outside the plane. In quantum wires, on the other hand, the spin polarization is dominated by interference effects induced by multiple scattering at the edges. Here, the spin polarization is quite sensitive to the value of the Fermi energy, especially close to the point where a new channel opens up. We analyzed different geometries and found that the spin polarization can be strongly enhanced.