Magnetic measurements on the layered III-VI diluted magnetic semiconductorGa1-xFexSe

Magnetic properties of single crystalline Ga1-xFexSe have been measured. Th is material is in the new class of diluted magnetic semiconductors based on the III-VI semiconductors. The magnetization versus field for an x = 0.05 sample deviates from the linear response seen previously in Ga1-xMnxSe and Ga1-xMnxS and reaches a maximum of 0.12 emu/g (<7% of the expected saturati on value) at 1.8 K in 7 T. Ga1-xFexSe exhibits an anisotropy below 2 T from 5 to 400 K with the hard axis perpendicular to the GaSe planes. Neither th e broad peak observed from 119-195 K in Ga1-xMnxSe nor the Curie-Weiss beha vior observed above 75 K in Ga1-xMnxS are observed in Ga1-xFexSe. The sharp cusp at 10.9 K in Ga1-xMnxS (characteristic of longer range ordering) is a lso not observed in Ga1-xFexSe in temperatures down to 1.8 K. In 0.1 T in t emperatures between 50 and 400 K, the magnetization drops to a roughly cons tant 0.004 emu/g. Below 5 K, the magnetization approaches a constant value of approximately 0.12 emu/g. The magnetic behavior of Ga1-xFexSe is consist ent with Van Vleck paramagnetism. (C) 2001 American Institute of Physics.