Interrelation between the magnetic properties and microstructure of thin La0.67Ca0.33MnO3 films

The results of the experimental investigation of magnetic and microstructural properties of thin films of La0.67Ca0.33MnO3 (LCMO) manganites grown by laser ablation on single-crystal (100) LaAlO3, LaGaO3, SrTiO3, and MgO substrates with subsequent heat treatment in oxygen, including the one under a high (100 bar) pressure, are presented. The influence of the inverse magnetostriction effect on the magnetic properties of the films is analyzed. Interrelation between the temperature dependence of the coercive force and anisotropic microstresses caused by the differences between the film and substrate lattice parameters and its variations after heat treatments in oxygen are investigated. The results are interpreted within the model of weak pinning of domain walls. The density of pinning centers is estimated. It is shown that only in the LCMO/MgO system, owing to the large value of anisotropic microstresses, the degree of imperfection of the film increases with increasing duration of heat treatment, which can be considered as one of the reasons for the appearance of electronic phase separation and related anomalies of magnetic and transport properties.