Non-linear spin to charge conversion in mesoscopic structures

TL;DR

This paper develops a non-linear theoretical framework for spin-to-charge conversion in quantum coherent mesoscopic structures, enabling detection of very small spin accumulations without magnetic fields.

Contribution

It introduces a novel non-linear theory showing how energy-dependent transmissions in mesoscopic constrictions convert spin currents into measurable electric signals.

Findings

Electric signals are quadratic in spin accumulation when transmission is spin-independent.

Gated mesoscopic constrictions can detect spin accumulations much smaller than 1% of the Fermi energy.

The theory aligns with recent experimental observations.

Abstract

Motivated by recent experiments [Vera-Marun et al., arXiv:1109.5969], we formulate a non-linear theory of spin transport in quantum coherent conductors. We show how a mesoscopic constriction with energy-dependent transmission can convert a spin current injected by a spin accumulation into an electric signal, relying neither on magnetic nor exchange fields. When the transmission through the constriction is spin-independent, the spin-charge coupling is non-linear, with an electric signal that is quadratic in the accumulation. We estimate that gated mesoscopic constrictions have a sensitivity that allows to detect accumulations much smaller than a percent of the Fermi energy.