Damping via the hyperfine interaction of a spin-rotation mode in a two-dimensional strongly magnetized electron plasma

TL;DR

This paper investigates the damping of a spin-rotation mode in a quantum Hall ferromagnet, revealing that hyperfine interactions with nuclei contribute to the dephasing process observed in Kerr precession experiments.

Contribution

It provides a microscopic analysis of nuclear hyperfine interactions as a damping mechanism for spin-rotation modes in strongly magnetized 2D electron systems, extending understanding beyond electron Landé factor fluctuations.

Findings

Hyperfine interaction causes longer dephasing times compared to electron Landé factor fluctuations.

The spin relaxation exhibits a longer quadratic stage before transitioning to linear decay.

Nuclear effects lead to a different temporal evolution of the spin-rotation mode.

Abstract

We address damping of a Goldstone spin-rotation mode emerging in a quantum Hall ferromagnet due to laser pulse excitation. Recent experimental data show that the attenuation mechanism, dephasing of the observed Kerr precession, is apparently related not only to spatial fluctuations of the electron Land\'e factor in the quantum well, but to a hyperfine interaction with nuclei, because local magnetization of GaAs nuclei should also experience spatial fluctuations. The motion of the macroscopic spin-rotation state is studied microscopically by solving a non-stationary Schr\"odinger equation. Comparison with the previously studied channel of transverse spin relaxation (attenuation of Kerr oscilations) shows that relaxation via nuclei involves a longer quadratic stage of time-dependance of the transverse spin, and, accordingly, an elongated transition to a linear stage, so that a linear time-dependance may not be revealed.