Theoretical and Experimental study of Multiferroic BiFeO3.

Nano-crystalline BiFeO3 was synthesized by chemical combustion route. Magnetic study revealed a ferromagnetic behavior at room temperature with magnetic coercivity of ~ 808 Oe. First principles GGA + U investigations for bulk systems indicate that for collinear orientation of magnetic moments, there are intra-plane ferromagnetic and inter-plane anti-ferromagnetic coupling. However, after incorporation of spin-orbital (SO) coupling, the system stabilizes into a canted spiral spin structure. Maintaining resemblance with experimental scenario, we have investigated nano-clusters of the same material, which under collinear orientation, follow similar magnetic order as bulk. With SO-coupling and the consequential non-collinear canting of the surface Fe ions, experimentally observed magnetic behavior could be quantitatively reproduced along with additional prediction interesting attributes like half-metallic nature. [ABSTRACT FROM AUTHOR]