Crossover critical behavior of Ga1-xMnxAs

Abstract

The critical behavior of the ferromagnetic semiconductor Ga1-xMnxAs with different concentrations of Mn was experimentally studied by thermal diffusivity measurements in close vicinity of the Curie temperature. Because the inverse of the thermal diffusivity has the same critical behavior as the specific heat, this allowed us to determine the critical exponent alpha for the samples investigated. As the critical temperature was approached, the value of the critical exponent alpha, for most of the samples under investigation, showed a clear crossover from the mean-field-like to the Ising-like critical behavior. Investigation of this crossover behavior has enabled us to determine the values of the Ginzburg number and the exchange interaction length in Ga1-xMnxAs.