Structural and magnetic properties of MnAs/GaAs ferromagnetic semiconductor nanocomposite material

Self-organized (Ga,Mn)As nanoclusters, embedded in GaAs and formed during thermal annealing of Ga1-xMnxAs layer at 500 °C or 600 °C, were studied using Transmission Electron Microscopy (TEM) and Magnetic Force Microscopy (MFM). We found that 10–20 nm large NiAs-type hexagonal MnAs nanocrystals gave magnetic contrast in MFM images, whereas smaller zinc-blende nanoinclusions were not visible by means of this technique. Theoretical simulations showed that MFM contrasts reflect interaction between magnetic tip and many randomly distributed MnAs nanocrystals.