Magnetic behavior of MnAs precipitates in Ga1-xMnxAs diluted magnetic semiconductor

Ferromagnetic Ga1-xMnxAs layers (where x approximate to 4.7-5.5%) were grown on (1 0 0) GaAs substrates by molecular beam epitaxy. These p-type (Ga,Mn) As films were revealed to have a ferromagnetic structure and ferromagnetism is observed up to a Curie temperature of 318 K, which is ascribed to the presence of MnAs secondary magnetic phases within the film. It is highly likely that the phase segregation occurs due to the high Mn cell temperature around 890-920 degrees C, as it is well established that GaMnAs is unstable at such a high temperature. The MnAs precipitate in the samples with x approximate to 4.7-5.5% has a Curie temperature T-c approximate to 318 K, which was characterized from field-cooled and zero-field-cooled magnetization curves. (C) 2007 Published by Elsevier B.V.