High Curie temperature GaMnAs obtained by resistance-monitored annealing

TL;DR

This study demonstrates that low-temperature annealing combined with resistivity monitoring during growth can significantly enhance the Curie temperature and conductivity of GaMnAs thin films, surpassing previous limits.

Contribution

It introduces a novel annealing process with resistivity monitoring that achieves higher Curie temperatures in GaMnAs films than previously reported.

Findings

Curie temperature reaches up to 140 K for x=0.06

Clear correlation between Tc and room temperature conductivity

Potential for further Tc improvements with optimized growth and annealing

Abstract

We show that by annealing Ga1-xMnxAs thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature Tc and conductivity can be obtained. Tc is unambiguously determined to be 118 K for Mn concentration x=0.05, 140 K for x=0.06, and 120 K for x=0.08. We also identify a clear correlation between Tc and the room temperature conductivity. The results indicate that Curie temperatures significantly in excess of the current values are achievable with improvements in growth and post-growth annealing conditions.