Negative magnetoresistance in magnetic semiconductors with narrow degenerate conduction bands

We propose a model to explain electrical conductivity anomalies in magnetic chalcogenide spinels near the Curie point. The model is based on strong electronelectron correlations between d-electrons in the narrow, orbitally degenerate conduction band. We demonstrate that in this system spin inhomogeneities produce scattering and lead to strong negative magnetoresistance. Experimental data on the electrical conductivity of the CdCr₂Se₄ compound in a magnetic field is compared to numerical computation. We explain the absence of magnetoresistance anomalies in p-type samples.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 10–14, December, 1986.