We show that by annealing Ga 1-x Mn x As thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature T C and conductivity can be obtained. T C 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 T C 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.

Vanishing of ferromagnetic order in (Ga,Mn)As films at high hole concentrations: beyond the mean field Zener model J. Appl. Phys. 103, 07D132 (2008); 10.1063/1.2836330Highly enhanced Curie temperature in low-temperature annealed [Ga,Mn]As epilayers Hall effect and magnetic properties of III-V based ( Ga 1−x Mn x ) As/AlAs magnetic semiconductor superlattices

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