CRYSTALLOGRAPHIC AND MAGNETIC-PROPERTIES OF ANTIFERROMAGNETIC CU0.5FE0.5RH2S4

Cu0.5Fe0.5Rh2S4 has been studied by Mossbauer spectroscopy, X-ray diff raction, and magnetic-susceptibility measurement. The crystal is found to have a cubic spinel structure with the lattice constant a(o)=9.835 +/-0.005 Angstrom. The iron ions are in ferric states and occupy the t etrahedral sites. The temperature dependence of the magnetic hyperfine field follows the Brillouin function for S=5/2. The Neel temperature and the paramagnetic Neel temperature are measured to be 135 and -384 K, respectively. The exchange interaction between second-nearest Fe ne ighbors is found to be J2=3.86 k(B), which is stronger than that betwe en first-nearest Fe neighbors, J1=3.56 k(B). Debye temperature is foun d to be 379+/-5 K.