Anomalous electron structure and magnetic properties in copper doped sulphur spinel

The Jahn-Teller distortional spinel compounds Fe1−xCuxCr2S4 (x=0.1, 0.5) with conduction mechanism are investigated. The Mössbauer spectra were recorded from 13 K to room temperature. The asymmetric line broadening was observed for the x=0.1 and considered to be the dynamic Jahn-Teller distortion. The unusual reduction of magnetic hyperfine field below 100 K may be explained in terms of cancellation effect between the mutually opposite orbital current field (HL) and Fermi contact field (HC). Mössbauer spectra identify that Fe ions occupy tetrahedral sites, the Cr ions occupy octahedral sites with a +3 valence in the Fe1−xCuxCr2S4 (x=0.1, 0.5). The charge state of Fe ions are ferrous (Fe2+) for the x=0.1, while Fe ions are ferric (Fe3+) for the x=0.5.