Electrical transport in epitaxial La0.7Ca0.3MnO3 thin films

We investigated the electrical transport properties of epitaxial La0.7Ca0.3MnO3 thin films grown by metal organic deposition process on LaAlO3 single crystalline substrates. To explain the coexistence of ferromagnetic (FM)-metallic and paramagnetic (PM) -insulator phases in the same specimen, the temperature dependence of resistivity was simulated by the phenomenological percolation model which is based on the phase segregation of FM-metallic to PM-insulator. The temperature dependence of resistivity (ρ(T)) curves can be well fitted by ρ(T)=ρFMf+ρPM(1−f) with ρFM is the resistivity of the FM phase below the Curie temperature (TC), ρPM is the resistivity of the PM phase above TC and “f” is the FM volume fraction. The obtained fitting parameters have been correlated to the change in the strain in the films having various thicknesses. The ferromagnetic volume fraction (f(T)) and the reduced magnetization m(T) show monotonic and “similar” behaviors.