Spin noise at electron paramagnetic resonance

TL;DR

This paper presents a microscopic theory of spin noise at electron paramagnetic resonance, revealing how RF fields influence the noise spectrum and enabling measurement of intrinsic electron spin lifetimes.

Contribution

It introduces a detailed theoretical framework describing spin noise under RF fields, including the emergence of Mollow-like triplets and narrow lines unaffected by inhomogeneous broadening.

Findings

RF fields split the spin noise spectrum into triplets.

Narrow lines in the spectrum are insensitive to g-factor dispersion.

Spin noise measurements can determine intrinsic electron spin lifetimes.

Abstract

We develop a microscopic theory of spin noise in solid-state systems at electron paramagnetic resonance, when the spin dynamics is driven by static and radio-frequency (RF) magnetic fields and the stochastic effective magnetic field stemming from the interaction with environment. The RF field splits the peaks in the power spectrum of spin noise into the Mollow-like triplets and also gives rise to additional spin-spin correlations which oscillate in the absolute time at the RF frequency and the double frequeqncy. Even in systems with strong inhomogeneous broadening, the spin noise spectrum contains narrow lines insensitive to the dispersion of the effective $g$-factors. Thus, the measurements of spin noise at electron paramagnetic resonance provides an access to the intrinsic spin lifetime of electrons.