Magnetic properties of La_(0.67)Sr_(0.33)MnO_3 epitaxial thin films grown on SrTiO_3(001)

摘要

Epitaxial La_(0.67)Sr_(0.33)MnO_3 thin films play important roles in several applications due to their half-metallic conductivity and high spin polarization. Since these properties are very sensitive to minor structural changes arising from slightly different growing conditions it is important to understand their effect on the electronic and magnetic properties of the resulting samples. Here, we study two sets of La_(0.67)Sr_(0.33)MnO_3 thin films, thicker (90 nm) and thinner (7 nm) ones, focusing on the influence of laser fluence and post-annealing oxygen partial pressure on their electronic structure and magnetism. Regardless of the preparation conditions, the thicker films present a tensile strain that leads to MnO_6 octahedral deformation as detected by Raman active modes. The thinner films exhibit sizable in-plane magnetic anisotropy which depends on the sample preparation that leads to distinct surface morphology and electronic properties (Mn~(4+)/Mn~(3+) ratio).