Effects of annealing time on defect-controlled ferromagnetism in Ga1−xMnxAs

Abstract

We have studied the evolution of the magnetic, electronic, and structural properties of annealed epilayers of ${\mathrm{Ga}}_{\text{1−x}}{\mathrm{Mn}}_x\mathrm{As}$ grown by low temperature molecular beam epitaxy. Annealing at the optimal temperature of $\text{250\hspace{0.05em}°}\mathrm{C}$ for less than 2 h significantly enhances the conductivity and ferromagnetism, but continuing the annealing for longer times suppresses both. These data indicate that such annealing induces the defects in ${\mathrm{Ga}}_{\text{1−x}}{\mathrm{Mn}}_x\mathrm{As}$ to evolve through at least two different processes, and they point to a complex interplay between the different defects and ferromagnetism in this material.