Magnetic and Electronic Structure of the CMR Chalcospinel Fe0.5Cu0.5Cr2S4

The search for magnetic analogues of superconducting compounds has lead to the discovery of compounds with giant magnetoresistance. For example, a colossal negative magnetoresistance of up to 20 % at 180 K has been measured for the chalcospinel Fe0.5Cu0.5Cr2S4. Here spin-polarized ab-initio band structure calculations are performed on the title compound in order to gain an understanding of its electronic and magnetic behavior, the structural information for these calculations being obtained from neutron diffraction data. The valency of iron is also investigated by temperature-dependent Mössbauer spectroscopy.