Magnetic states and valence fluctuations in charge frustrated polycrystalline lutetium ferrite samples

LuFe2O4 polycrystalline materials were processed by an innovative protocol using high-energy ball milling and thermal treatments in an argon flux. The results of room-temperature Mössbauer spectroscopy showed different concentrations of Fe2+ and Fe3+ in samples treated for different time periods. Magnetic studies revealed multiple magnetic transitions and showed that valence fluctuations resulted in samples with distinguishable magnetic behaviors. In fact, an additional anomaly in the M × T curve was observed for the LuFe2O4 sample thermally treated for 1 h at 1473 K.