Fourfold symmetric planar Hall effect in epitaxial La1-xSrxCoO3 thin films

The effect of Sr concentration on the planar Hall effect (PHE) in epitaxial magnetic phase separated La1-xSrxCoO3 (0.07 <= x <= 0.60) thin films was studied systematically. It was found that crystalline anisotropy and spin-orbital coupling are the main contributions to the unexpected fourfold symmetric PHE. The uniaxial anisotropy field was given by H-uni = 70 Oe and cubic anisotropic field H-cub = 143 Oe, respectively. The magnetic anisotropy was weakened by Sr doping, which corresponds with the disappearance of the fourfold symmetry in PHE with the increasing Sr concentration. The first principle calculations proved that the contribution of Co-d orbitals to the magnetic anisotropy strongly depends on the Sr concentration. e(g) - d(x2) (- y2) and e(g) - d(3z2 - r2) orbitals play a dominant role in the magnetic anisotropy of the samples with x = 0.125, 0.25, while the t(2g) - d(xy); d(yz), d(xz) orbitals contribute mainly to the magnetic anisotropy of the samples with x = 0.375, 0.5, 0.625. (C) 2015 AIP Publishing LLC.