Magnetic properties of the new diluted magnetic semiconductor : evidence of MnAs clusters

The preparation and magnetic properties of the diluted magnetic semiconductor , opening a novel group of compounds alloyed with transition metal elements, are reported for the first time. Single crystals of are obtained with a modified Bridgman method. For their structure is isomorphic to the parent compound. Magnetic properties of are investigated for x = 0.01, 0.05 and 0.1 between T = 2 and 500 K in fields up to 60 kG. All the samples show a steep decrease of magnetization well above 300 K. In low fields (2-200 G) the temperature dependence of the magnetic susceptibility is strongly irreversible below K. The magnetization displays nonlinear field dependence starting from -2 kG and reaching full saturation above 40 kG. Its temperature dependence is weak between 2 and 300 K. The magnetic properties are explained by the presence of MnAs clusters. The distribution of cluster sizes is described by three overlapping Gaussian functions with the maxima at 1.7, 2.4 and 3.3 nm. At 300 K the corresponding magnetic moments are found to be 1.5, 4.1 and 10.4 in units of .