Effects of annealing procedures on the structural and magnetic properties of epitaxial La0.7Sr0.3MnO3 films

The effects of annealing procedures on the structural and magnetic properties of the LSMO films epitaxially grown on (1 0 0) LaAlO3 (LAO) and SrTiO3 (STO) substrates have been studied. A gradual lattice contraction is observed with the increase of annealing temperatures. This can be explained as the increase in Mn4+/Mn3+ ratio before it reached the ideal one value (3:7). Annealing procedures at the higher temperatures can enhance the ferromagnetic order and Curie temperature (Tc) and dramatically reduce the coercivity values due to the increase in the oxygen content. On the other hand, a larger surface roughness caused by the lattice mismatch between the films and the substrates is presumably responsible for a higher coercivity.