Low temperature ferromagnetism, surface paramagnetism and exchange bias effect in nano-grained alpha-Fe1.4Ga0.6O3 oxide

摘要

The compound alpha-Fe1.4Ga0.6O3 has been prepared by mechanical alloying ofalpha-Fe2O3 and Ga2O3 and subsequent heating of the mechanical alloyed samplesin vacuum condition. Magnetic ordering of alpha-Fe2O3 has been modified bysubstitution of non-magnetic Ga atoms. The ferromagnetism in alpha-Fe1.4Ga0.6O3is more soft and enhanced in comparison to alpha-Fe2O3. M\"ossbauerspectroscopy also confirmed enhanced ferromagnetic order in alpha-Fe1.4Ga0.6O3.The room temperature soft ferromagnetism by Ga substitution is interesting fordesigning alpha-Fe2O3 based unconventional ferromagnet, which is a greatchallenge to the materials scientists. The alpha-Fe1.4Ga0.6O3 samples alsoexhibited features of exchange bias, low temperature surface paramagnetism, andsuppression of Morin transition. These features have been affected up tocertain extent by the nano-sized grains of the samples.