Multiferroic nanocrystalline BiFeO3 and BiCrO3 thin films prepared by ion beam sputtering

Abstract

BiFeO3 and BiCrO3 films were made by room temperature sputtering followed by thermal annealing in a partial oxygen atmosphere. The annealed films were found to be nanocrystalline, with an average particle size of 11 nm for BiFeO3 and 8 nm for BiCrO3. The saturation moment per formula unit is 0.39 μB for BiFeO3 which is significantly greater than that found in bulk BiFeO3 (0.02 μB). A similar enhancement was also found in previous studies of BiFeO3 nanoparticles where the nanoparticle size was small. However, no large enhancement of the saturation moment per formula unit was identified for the annealed BiCrO3 films. The annealed BiFeO3 films displayed superparamagnetic behaviour and the parti..