Spin current and accumulation generated by spin Hall insulator

TL;DR

This paper theoretically investigates how electric fields induce spin currents and accumulation in spin Hall insulators, highlighting the roles of hybridization, boundary effects, and leakage currents in spin transport phenomena.

Contribution

It provides a theoretical analysis of spin current generation and accumulation in spin Hall insulators using the Keldysh formalism, contrasting with quantum Hall systems.

Findings

Spin current is generated near electrode contacts.

Spin current is truncated by spin sinks and sources.

Leakage charge current causes spin accumulation.

Abstract

Spin current and accumulation generated by the electric field in spin Hall insulator (SHI) are investigated theoretically in terms of the Keldysh formalism. In contrast to the quantum Hall system, there are no massless edge modes in general. The spin current is generated near the contacts to the electrodes by the hybridization between the metallic states and the conduction/valence bands of the SHI, but is truncated by the sink and source of the spin. However, one can produce the spin current flowing out to the conductors, which is attached to the SHI, and also the spin accumulation there due to the leakage charge current which breaks the time-reversal symmetry.