Spin-to-Charge Conversion of Mesoscopic Spin Currents

TL;DR

This paper proposes a method to measure mesoscopic spin currents generated by electric currents in spin-orbit coupled systems using a single-channel voltage probe, linking charge current behavior to spin current magnitude.

Contribution

It introduces a novel measurement technique for mesoscopic spin currents via charge current asymmetries in a quantum point contact under Zeeman fields.

Findings

Charge current through quantum point contact is odd in magnetic field when spin current is present.

Zero-field derivative of charge current is proportional to spin current magnitude.

Numerical confirmation of the measurement method.

Abstract

Recent theoretical investigations have shown that spin currents can be generated by passing electric currents through spin-orbit coupled mesoscopic systems. Measuring these spin currents has however not been achieved to date. We show how mesoscopic spin currents in lateral heterostructures can be measured with a single-channel voltage probe. In the presence of a spin current, the charge current $I_{\rm qpc}$ through the quantum point contact connecting the probe is odd in an externally applied Zeeman field $B$, while it is even in the absence of spin current. Furthermore, the zero field derivative $\partial_B I_{\rm qpc}$ is proportional to the magnitude of the spin current, with a proportionality coefficient that can be determined in an independent measurement. We confirm these findings numerically.