Correlation effects in the density of states of annealed GaMnAs

TL;DR

This study investigates how low temperature annealing affects the correlation gap in the density of states of GaMnAs, revealing modifications in electron-electron interactions through tunnelling conductance measurements.

Contribution

It provides experimental evidence that annealing can tune the correlation gap in GaMnAs, advancing understanding of electron interactions in this material.

Findings

Annealing modifies the correlation gap in GaMnAs.

Conductance shows a root mean square V dependence.

Transition observed across the phase boundary between correlation regimes.

Abstract

We report on an experimental study of low temperature tunnelling in hybrid NbTiN/GaMnAs structures. The conductance measurements display a root mean square V dependence, consistent with the opening of a correlation gap in the density of states of GaMnAs. Our experiment shows that low temperature annealing is a direct empirical tool that modifies the correlation gap and thus the electron-electron interaction. Consistent with previous results on boron-doped silicon we find, as a function of voltage, a transition across the phase boundary delimiting the direct and exchange correlation regime.