Anomalous magnetic properties of the ferrimagnetic semiconductor on Ga-doped sulphur spinel

Abstract

FeGa x Cr 2−x S 4 (x=0.1 and 0.3) have been studied with Mössbauer spectroscopy, x-ray diffraction, magnetization, and magnetoresistance. Fe ions migrate from the tetrahedral (A) site to the octahedral (B) site with an increase of Ga substitutions. The electric quadrupole splitting of the A and B sites in Mössbauer spectra of the sample x=0.1 at 295 K, are 0.30 and 2.93 mm/s, respectively, whereas, for the sample x=0.3 they are 0.83 and 2.94 mm/s, respectively. It gives a direct evidence that Ga ions stimulate the asymmetric charge distribution of Fe ions in the A site. The temperature dependence of quadrupole interaction leads to the conclusion that orbital angular contribution plays an important role in FeGaxCr2−xS4 (x=0.1 and 0.3).