A Monte Carlo study of critical properties of strongly diluted magnetic semiconductor (Ga,Mn)As

Abstract

Within a Monte Carlo technique we examine critical properties of diluted bulk magnetic semiconductor (Ga,Mn)As modeled by a strongly diluted ferromagnetic Heisenberg spin-$\frac{5}{2}$ system on a face centered cubic lattice. We assumed that 5\% of Ga atoms is substituted by Mn atoms and the interaction between them is of the RKKY-type. The considered system is randomly quenched and a double average was performed: firstly, over the Boltzmann probability distribution and secondly - over 2048 configurations related to the quenched disorder. We estimated the critical temperature: $T_c=97\pm6$ K, which is in agreement with the experiment. The calculated high value of critical exponent $\nu$ seems to point to a possibility of non-universal critical behavior.