Warm-up spectroscopy of quadrupole-split nuclear spins in n-GaAs epitaxial layers

TL;DR

This paper introduces warm-up spectroscopy to analyze nuclear spin temperature changes in n-GaAs layers with quadrupole interactions, providing insights into electric field gradients and nuclear spin thermodynamics despite quadrupole effects.

Contribution

It demonstrates the use of warm-up spectroscopy to characterize quadrupole effects and electric field gradients in n-GaAs, validating the thermodynamic description of nuclear spin systems under these conditions.

Findings

Determined electric field gradient tensors for 75As and Ga isotopes.

Validated the thermodynamic description of NSS with quadrupole interactions.

Analyzed the impact of mechanical strain and electric fields on NSS temperature.

Abstract

The efficiency of the adiabatic demagnetization of nuclear spin system (NSS) of a solid is limited, if quadrupole effects are present. Nevertheless, despite a considerable quadrupole interaction, recent experiments validated the thermodynamic description of the NSS in GaAs. This suggests that nuclear spin temperature can be used as the universal indicator of the NSS state in presence of external perturbations. We implement this idea by analyzing the modification of the NSS temperature in response to an oscillating magnetic field at various frequencies, an approach termed as the warm-up spectroscopy. It is tested in a n-GaAs sample where both mechanical strain and built-in electric field may contribute to the quadrupole splitting, yielding the parameters of electric field gradient tensors for 75As and both Ga isotopes, 69Ga and 71Ga.