The magnetism of Zn-doped colossal magnetoresistance materials Fe1−xZnxCr2S4 (0⩽x⩽1)

Abstract The polycrystalline samples of Zn-doped Fe 1− x Zn x Cr 2 S 4 (0⩽ x ⩽1) were prepared by the conventional solid-state synthesis method. The magnetic homogeneity has been proved by the measurements of the alternating current (AC) magnetic susceptibility. We presented a detailed study of Zn-doping effect on the magnetism. It is found that the magnetism does not change monotonically with substituting nonmagnetic Zn 2+ ions for Fe 2+ ions. The difference between the magnetic moments for the samples with respective doping level can be ascribed to the variation of compensation between the Fe 2+ and Cr 3+ sublattices as the Fe 2+ concentration is varied. The Zn-doping leads to spin reversal of Cr 3+ ions. Based on the spin orientation of Fe 2+ and Cr 3+ ions in FeCr 2 S 4 and ZnCr 2 S 4 at 0 K, we suggest a phenomenological model describing the magnetism and the doping level dependence of the up-spin proportion of Cr 3+ ions. The up-spin proportion of Cr 3+ ions, denoted by y , as a function of doping level in zero fields is linear. However, y in magnetic fields cannot be fitted linearly, which shows a maximum. The above results can be described qualitatively by the effect of the applied magnetic field on the AB, AA, and BB interactions of the spinels with the formula ABS 4 .