Magnetism and electrical transport properties of La1-x-yPryCaxMnO3 (x approximate to 0.42, y approximate to 0.40) thin films: role of microstructural disorder

We report the effect of substrate-induced lattice disorder on the balance between the coexisting antiferromagnetic/charge-ordered insulating (AFM/COI) and ferromagnetic metallic (FMM) phases and the dynamics of the phase transition in the strongly phase-separated single-crystalline La1-x-yPryCaxMnO3 (x approximate to 0.42, y approximate to 0.40) thin films. At lower degree of disorder, the delicate balance between AFM/COI and FMM phases gives rise to a magnetically disordered/non-equilibrium magnetic liquid, which shows a strong supercooling behaviour and colossal thermal hysteresis in temperature dependence of magnetization (M-T) and resistivity (rho-T). At lower temperatures, the disordered liquid freezes to yield a randomly frozen glassy state. The enhanced lattice disorder quenches the non-FM phases and promotes AFM/COI-FMM phase transition, which in turn reduces the magnetic frustration and lowers the degree of supercooling. The enhanced FMM fraction also unblocks the blocked magnetic states and results in the vanishing of the pronounced minimum in the rho-T curve observed well above the glass transition. Our results show that the impact of enhanced lattice disorder is in many ways similar to that of the extrinsic magneto-thermodynamic perturbations.