Anomalous strain effect in La0.8Ba0.2MnO3 epitaxial thin film:: Role of the orbital degree of freedom in stabilizing ferromagnetism -: art. no. 224418

We achieved enhancement of colossal magnetoresistance at room temperature in a tensile strained La0.8Ba0.2MnO3 thin film (52% at 297 K under an applied field of 0.8 T). Surprisingly, the tensile strain increased the Curie temperature T-C from 270 K in the bulk to 320 K in the thin film. While it is well known that tensile strain decreases T-C through a decrease of the transfer integral to in (La, D) MnO3 (D = Ca or Sr), this unprecedented anomalous strain effect in La0.8Ba0.2MnO3 films could not be explained by to alone: the orbital degree of freedom also needed to be considered. We successfully derived an equation for T-C including both effects in the strained thin films.