Percolative model of the effect of disorder on the resistive peak broadening in La2/3Ca1/3MnO3 near the metal-insulator transition

The effect of the lattice disorder on the resistivity of La1-xCaxMnO3 (LCMO) near x=1/3 at the metal-insulator transition was studied by using a percolation model. The percolation model was applied to calculate the temperature dependence of the resistivity rho(T) of the mixed state, where metallic ferromagnetic and insulating paramagnetic clusters simultaneously exist. The temperature dependence of the fraction of the metallic phase was obtained by assuming a Gaussian distribution of random transition temperatures, whose width increases with an increasing lattice disorder. The resistivity rho(T) calculated from the model reproduces well the experimental ones for LCMO crystals and disordered films. (C) 2008 American Institute of Physics.