Helicity asymmetry of optically-pumped NMR spectra in GaAs

TL;DR

This paper analytically derives and experimentally tests the origins of helicity asymmetries in optically-pumped NMR spectra of GaAs, linking asymmetries to electron polarization and local temperature variations.

Contribution

It provides a new analytical framework and experimental validation for understanding helicity asymmetries in GaAs NMR signals, highlighting the role of electron polarization.

Findings

Asymmetry ratios depend on photon energy and laser power.

Local temperature and electron polarization can be extracted from asymmetry data.

Other factors influencing asymmetry are also discussed.

Abstract

The origin of helicity asymmetries in the optically-pumped NMR signal and hyperfine shift in GaAs is derived analytically and tested experimentally. The ratio of the optically-pumped to the equilibrium electron polarizations is a key parameter in determining both asymmetries. Variations in asymmetry with photon energy and laser power reflect variations in the local temperature and the electron spin polarization, and these two quantities are extracted from the asymmetry through a simple methodology. Other contributions to the asymmetry are considered.