Spin-Orbit Scattering and Time-Reversal Symmetry: Detection of a Spin by Tunneling

TL;DR

This paper explores how spin precession can be detected through nonequilibrium transport, highlighting the constraints imposed by time-reversal symmetry and the conditions needed for observing signals near the Larmor frequency.

Contribution

It demonstrates the effects of time-reversal symmetry on spin detection via tunneling and identifies conditions under which spin precession signals can be observed.

Findings

Periodic current signals result from beating of two precession frequencies.

Detecting signals near the Larmor frequency requires specific conditions such as zero g-factor.

Strong magnetic fields or spin polarization are necessary for certain detection scenarios.

Abstract

We consider the possibility of detecting spin precession in a magnetic field by nonequilibrium transport processes. We find that time reversal symmetry imposes strong constraints on the problem. Suppose the tunneling occurs directly between systems at two different chemical potentials, rather than sequentially via a third system at an intermediate chemical potential. Then, unless the magnetic fields are extremely strong or spin polarized electrons are used, the periodic signal in the current results from beating together two different precession frequencies, so that observing a signal near the Larmor frequency in this case requires having some cluster with a $g$ factor close to zero.