Mechanical measurement of equilibrium spin currents in the Rashba medium

TL;DR

This paper shows that equilibrium spin currents in a Rashba medium induce measurable mechanical torques on substrates, providing a new way to detect spin currents and revealing edge states that form a spin-orbit quantum wire.

Contribution

It introduces a mechanical detection method for equilibrium spin currents in Rashba media and uncovers localized edge states forming a spin-orbit quantum wire.

Findings

Equilibrium spin currents cause measurable torque on substrates.

Edge states form a 1D continuum, indicating a new quantum wire type.

Magnetic fields can enhance and tune the effect.

Abstract

We demonstrate that an equilibrium spin current in a 2D electron gas with Rashba spin-orbit interaction (Rashba medium) results in a mechanical torque on a substrate near an edge of the medium. If the substrate is a cantilever, the mechanical torque displaces the free end of the cantilever. The effect can be enhanced and tuned by a magnetic field. Observation of this displacement would be an effective method to prove existence of equilibrium spin currents. The analysis of edges of the Rashba medium demonstrates the existence of localized edge states. They form a 1D continuum of states. This suggests a new type of quantum wire: spin-orbit quantum wire.