Achieving High Curie Temperature in (Ga,Mn)As

TL;DR

This study investigates how growth conditions and annealing affect the Curie temperature of (Ga,Mn)As layers, demonstrating that optimizing these parameters can significantly enhance ferromagnetic properties.

Contribution

The paper identifies optimal growth and annealing conditions to maximize the Curie temperature in (Ga,Mn)As, highlighting the balance between Mn removal and temperature effects.

Findings

Highest Tc achieved near the 2D-3D phase boundary.

Post-growth annealing increases Tc by removing interstitial Mn.

Higher annealing temperatures can reduce Tc due to competing processes.

Abstract

We study the effects of growth temperature, Ga:As ratio and post-growth annealing procedure on the Curie temperature, Tc, of (Ga,Mn)As layers grown by molecular beam epitaxy. We achieve the highest Tc values for growth temperatures very close to the 2D-3D phase boundary. The increase in Tc, due to the removal of interstitial Mn by post growth annealing, is counteracted by a second process which reduces Tc and which is more effective at higher annealing temperatures. Our results show that it is necessary to optimize the growth parameters and post growth annealing procedure to obtain the highest Tc.