Antiferromagnetism and spin-glass transition in the FeInxCr2−xSe4 series of selenides

The magnetic behavior of the FeInxCr2−xSe4 system (with x=0.0, 0.2 and 0.4) has been investigated by magnetic and Mössbauer spectroscopy. Hyperfine parameters indicate that iron is in the Fe2+ oxidation state, with a minor (∼9%) Fe3+ fraction, located at different layers in the structure. Low-field magnetization curves as a function of temperature showed that the antiferromagnetic (AFM) order temperature is TN=208(2) K for FeCr2Se4 and decreases to 174(3) K for FeIn0.4Cr1.6Se4. The effective magnetic moment μeff decreases with increasing In contents, and shows agreement with the expected values from the contribution of Fe2+ (5D) and Cr3+ (4F) electronic states. A second, low-temperature transition is observed at TG∼13 K, which has been assigned to the onset of a glassy state.