Nonequilibrium spin noise spectroscopy

TL;DR

This paper investigates how spin noise spectroscopy can reveal information about spin-orbit coupling anisotropy and electron spin dynamics in weakly non-equilibrium conditions induced by electric currents.

Contribution

It demonstrates that electric currents cause a measurable shift in the spin noise spectrum related to spin-orbit coupling, expanding SNS applications.

Findings

Noise power spectrum shifts proportionally with spin-orbit coupling strength.

Electric current induces measurable changes in spin noise spectra.

Potential to distinguish between conducting and localized electron spin noise.

Abstract

Spin Noise Spectroscopy (SNS) is an experimental approach to obtain correlators of mesoscopic spin fluctuations in time by purely optical means. We explore the information that this technique can provide when it is applied to a weakly non-equilibrium regime when an electric current is driven through a sample by an electric field. We find that the noise power spectrum of conducting electrons experiences a shift, which is proportional to the strength of the spin-orbit coupling for electrons moving along the electric field direction. We propose applications of this effect to measurements of spin orbit coupling anisotropy and separation of spin noise of conducting and localized electrons.