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

We investigated the electrical transport properties of epitaxial La 0.7 Ca 0.3 MnO 3 thin films grown by metal organic deposition process on LaAlO 3 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 ) = ρ FM f + ρ PM ( 1 − f ) with ρ FM is the resistivity of the FM phase below the Curie temperature ( T C ), ρ PM is the resistivity of the PM phase above T C 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. [ABSTRACT FROM AUTHOR]