Heterogeneous nucleation and metal-insulator transition in epitaxial films of NdNiO3

We have investigated the temperature driven first order metal-insulator (M-I) transition in thin films of NdNiO3 and have compared it with the bulk behavior. The M-I transition of thin films is sensitive to epitaxial strain and its partial relaxation creates an inhomogeneous strain field in the films which broadens the M-I transition. Both the thin film and the bulk samples exhibit nonequilibrium features in the transition regime which are attributed to the presence of high temperature metallic phases in their supercooled state. The degree of supercooling in the thin films is found to be much smaller than in the bulk which suggests that the M-I transition in the thin film occurs through heterogeneous nucleation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3481396]