Enhanced ferromagnetism of cluster-assembled BiFeO3 nanostructured films

•Well-defined BiFeO3 nanostructured films were assembled with 0-dimension clusters.•Noticeably enhanced ferromagnetism is observed for the cluster-assembled BiFeO3 films.•BiFeO3 films were assembled with nearly spherical and densely packed nanoparticles.

Cluster-assembled BiFeO3 nanostructured films were prepared using low-energy cluster beam deposition method with our homemade cluster apparatus. It is shown that the nanostructured films are perovskite structure and assembled uniformly and compactly with monodisperse spherical clusters with average diameter of ~ 22 nm. The enhanced ferromagnetism is observed for the as-prepared films, which is attributed to the uncompensated surface spins and the release of the latent magnetization locked within the cycloid induced by the size effect of the clusters with the smaller characteristic size than the long-range cycloid order of 62 nm. The present work provides a way on enhancing ferromagnetism of single-phase multiferroics.