Are strain-induced effects truly strain induced? A comprehensive study of strained LCMO thin films

Abstract

We report results on strained ${\mathrm{La}}_{2∕3}{\mathrm{Ca}}_{1∕3}\mathrm{Mn}{\mathrm{O}}_3$ (LCMO) films that are able to distinguish between true strain effects and effects due simply to the reduced film thickness. Biaxially strained LCMO films were grown on $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ , $\mathrm{Nd}\mathrm{Ga}{\mathrm{O}}_3$ , and $\mathrm{La}\mathrm{Al}{\mathrm{O}}_3$ . The films on $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ and $\mathrm{La}\mathrm{Al}{\mathrm{O}}_3$ are elastically strained and those on $\mathrm{Nd}\mathrm{Ga}{\mathrm{O}}_3$ are only slightly strained. We observe that both the saturation moment $\left(M_{\mathrm{sat}}\right)$ and the Curie temperature $\left(T_{\mathrm{C}}\right)$ are suppressed as the films become thinner, regardless of the strain. Thus, the decrease in $M_{\mathrm{sat}}$ and $T_{\mathrm{C}}$ is due to the two-dimensional nature of the films and not the strain.