Interplay between magnetic order and the vibrational state of Fe in FeCr2S4 Original Research Article

The temperature dependence of the 57Fe Mössbauer recoilless fraction, and that of the local electronic and magnetic state of iron in the chalcogenide spinel FeCr2S4 have been studied in detail around the Curie temperature with the help of 57Fe Mössbauer spectroscopy. Ferrimagnetic order was found to break down anomalously at ∼20 K below the Curie temperature in FeCr2S4. Magnetic relaxation of iron magnetic moments was observed with increasing relaxation rate above T∼155 K. The local Debye temperature as well as the effective vibrating mass, representative for the local vibrational state of iron, was found to be considerably higher in the paramagnetic state than in the magnetically ordered state. At long range magnetic order was found to develop in response to 6 T external magnetic field showing that in FeCr2S4 short-range magnetic order persists well above the Curie temperature.