Magnetic non-uniformity and thermal hysteresis of magnetism in a manganite thin film

We measured the chemical and magnetic depth profiles of a single crystalline (La$_{1-x}$Pr$_x$)$_{1-y}$Ca$_y$MnO$_{3-δ}$ (x = 0.52\pm0.05, y = 0.23\pm0.04, δ = 0.14\pm0.10) film grown on a NdGaO3 substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first order ferromagnetic transition at low temperatures.