Strong uniaxial in-plane magnetic anisotropy of (001)- and (011)-oriented La_(0.67)Sr_(0.33)MnO_3 thin films on NdGaO_3 substrates

摘要

Epitaxial La_(0.67)Sr_(0.33)MnO_3 (LSMO) ferromagnetic thin films were coherently grown on NdGaO_3 (NGO) substrates with different crystal orientations of the surface plane. On the (110)_o- and (001)_o-oriented substrates, the film grows in the (001)_(pc) orientation, and on the (100)_(o~-), (010)_(o~-), and (112)_(o~-)-oriented substrates the film is (011)_(pc) oriented (we will use subindices o and pc for the orthorhombic and pseudocubic crystal structures, respectively). The lattice parameters and pseudocube angles of the deformed LSMO pseudocube have been determined from x-ray diffraction measurements. The in-plane magnetic easy and hard directions of these films have been determined from the dependence of the remnant magnetization on the angle of the in-plane applied field. For all substrate orientations there is a strong in-plane uniaxial magnetic anisotropy, determined by the crystal directions of the substrate surface. The easy and hard magnetic-anisotropy directions are explained consistently by the (bulk) inverse magnetostriction model, except for the film on NGO (112)_o.