Aharonov-Casher and spin Hall effects in two-dimensional mesoscopic ring structures with strong spin-orbit interaction

TL;DR

This paper investigates quantum interference and spin Hall effects in two-dimensional mesoscopic ring structures with strong, tunable spin-orbit interaction, revealing how carrier density and inhomogeneous SO coupling influence conductance and spin transport.

Contribution

It provides a detailed analysis of how electrically tunable spin-orbit coupling affects quantum interference and spin Hall effects in 2D ring structures, including inhomogeneous cases.

Findings

Conductance can be modulated by SO splitting and carrier density.

Pronounced resonances occur when Fermi energy aligns with ring eigenenergies.

Heavy-hole carriers exhibit larger spin Hall and longitudinal conductivities than electrons.

Abstract

We study the quantum interference effects induced by the Aharonov-Casher phase in asymmetrically confined two-dimensional electron and heavy-hole ring structures systems taking into account the electrically tunable spin-orbit (SO) interaction. We have calculated the non-adiabatic transport properties of charges (heavy-holes and electrons) in two-probe thin ring structures and compare how the form of the SO coupling of the carries affects it. We show that both the SO splitting of the bands and the carrier density can be used to modulate the conductance through the ring. We show that the dependence on carrier density is due to the backscattering from the leads which shows pronounce resonances when the Fermi energy is close to the eigenenergy of the ring. We also calculate the spin Hall conductivity and longitudinal conductivity in four-probe rings as a function of the carrier density and SO interaction, demonstrating that for heavy-hole carriers both conductivities are larger than for electrons. Finally, we investigate the transport properties of mesoscopic rings with spatially inhomogeneous SO coupling. We show that devices with inhomogeneous SO interaction exhibit an electrically controlled spin-flipping mechanism.