Study of surface magnetism, exchange bias effect, and enhanced ferromagnetism in α-Fe1.4Ti0.6O3 alloy

Magnetic properties of mechanical alloyed alpha-Fe1.4Ti0.6O3 were studied at broad scale of temperatures, starting from room temperature down to 5 K. Morin transition of the base compound alpha-Fe2O3 was not observed after Ti doping. Enhanced ferromagnetism and exchange bias effect were exhibited in the alloyed compound alpha-Fe1.4Ti0.6O3. The observations were examined from different aspects of the alloying process, e. g., magnetic solution (spin ordering) at the interfaces of rhombohedral planes and core-shell structure of the nano-grains. Interfacial magnetic modifications were seen to be affected by the factors associated with grain size variation during alloy formation and thermal annealing of the alloy. Detailed analyses were made to understand the surface magnetism and exchange bias effect in the samples. Magnetic features of the present samples in many cases were found to be unconventional in comparison with the simple grain size effect of magnetic particles. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3585663]