Spin-Ordering Leading Magnetic Transition in Sulphur System \hbox\hbox ( \hbox=\hbox and Zn)

Magnetic structure of Fe 1-x Zn x Cr 2 S 4 (0.1 les x les 0.9) has been studied with magnetic susceptibility, X-ray diffraction and Mossbauer spectra. The crystal structures are found to have a cubic spinel with space group Fd3m. The lattice constants decrease with increasing Zn concentrations. According to magnetic susceptibility measurements, Neel temperature (T N ) decreases with increasing Zn concentrations from x=0.5 to 0.7, especially T N dramatically decreases from 105 K to 45 K. The magnetic ground state reveal transition from ferrimagnetic to anti-ferromagnetic behavior at x=0.7. It is interpreted that the order of magnetic ions between tetrahedral (A) site ion and octahedral (B) site ion is antiparallel. The Mossbauer spectra show asymmetrical shapes due to large electric quadrupole interaction, magnetic hyperfine field of samples decrease in ferrimagnetic behavior ranges and increase in antiferromagnetic behavior ranges at 4.2 K. The magnetic hyperfine field of all samples for Zn concentration x = 0.1, 0.3, 0.5, 0.7 and 0.9 are 156, 128, 116, 131 and 138 kOe, respectively. It is described that the magnetic dipole interaction was weakened as substituting Zn ions in replacement of Fe on A site.