Explorations of the magnetization of Ga1-xMnxS over a wide range of concentrations, 0.008 \u3c x \u3c 0.18

Calculations and measurements of the magnetization of Ga1-xMnxS, a III-VI diluted magnetic semiconductor crystal, are reported. Results extend over a wide range of concentrations: x=0.18, 0.13, 0.099, 0.079, 0.062, 0.032, and 0.008. The magnetization was measured at temperatures from 50 to 400 K in magnetic fields up to 7 T. The experimental data are compared with a model of the magnetization that is derived using the energy levels of a singlet Hamiltonian which posits the manganese atoms are not interacting with each other. The Hamiltonian consists of crystal-field, spin-orbit, spin-spin, and Zeeman interactions of the 3d electrons of the Mn+3 substitutional ions. The spin-orbit parameter used in the model was lambda=23 cm(-1), independent of concentration. At smaller values of x the singlet model agreement with the experiment is excellent. For larger values of x and low temperatures the agreement deteriorates somewhat as expected due to the antiferromagnetic coupling of the Mn ions. (C) 2006 American Institute of Physics