Structure, magnetic and transport properties of La_0.7Ca_0.3-xSr_xMnO₃ thin films by sol-gel method

La_0.7Ca_0.3-xSr_xMnO₃ (x=0, 0.10, 0.15, 0.25 and 0.30) thin films were prepared by the sol-gel method on Si substrates. The structural, magnetic and transport properties were systematically studied. All the LCSMO thin films crystallized perfectly with a random crystalline orientation. The films show strong coupling between lattice and physical properties. With the increment in x, the lattice parameter increases, the magnetic properties are enhanced, and the Tc increases monotonically from 235 K to 343 K. Resistivity is dramatically decreased with Sr dopant. The temperature corresponding to the MR maxmium value is close to that of the T_MI for LCMO, while there was no peak value for Sr doped thin films in this temperature range.