Scaling roughness and transport properties correlation in manganite thin films

A scaling roughness study was done on digitized Atomic Force Microscope (AFM) images of La$_{2/3}$Ca$_{1/3}$MnO$_{3}$ thin films grown on (100) oriented SrTiO$_{3}$ substrates. The films were grown via sputtering technique at high oxygen pressures (mbar) and at substrate temperatures of 850 $^{\circ}$C. The films were characterized by resistivity measurements to determine the Curie temperature by the transition temperature from insulating to metallic phase. From digitized AFM-images and by using a specific self-designed algorithm, we statistically study the scaling roughness properties. We obtain quantitative values for the roughness parameters: interface width ($\sigma )$, correlation length ($\xi )$, and roughness exponent ($\alpha )$. The calculated $\alpha $-values are 0.85 $\pm $ 0.05, indicating a highly oriented growth mechanism. We analyzed the dependence of layer thickness (d) and image size (D) with the parameters describing roughness and founded that Curie-Temperature is correlated with the lateral correlation length whereas there is no correlation with the saturation roughness.