Low temperature magnetic ordering in Fe-doped TiO2 samples

Fe-doped TiO2 samples with different Fe content prepared by mechanical alloying have been investigated by means of Moessbauer spectroscopy at 300 and 4.2 K. The results indicate the coexistence of Fe2+ and Fe3+ ions in paramagnetic states at room temperatures in the rutile structure. All samples present magnetic order at 4.3 K. When the Fe concentration increases the Fe ions in the rutile matrix became closer giving the possibility of strong magnetic interactions between them. The temperature evolution of the magnetic order was followed for the 15 at.% of Fe sample. The Fe-doped oxide formed for this composition orders below 20 K reaching an almost totally magnetic ordered state at 4.3 K.