Magnetic anisotropy and valence states in La2Co1−xMn1+xO6 ( x≈0.23 ) thin films studied by x-ray absorption spectroscopy techniques

X-ray absorption spectroscopy was used to determine the valence state in $\mathrm{L}{\mathrm{a}}₂\mathrm{C}{\mathrm{o}}_{1\ensuremath{-}x}\mathrm{M}{\mathrm{n}}_1+x{\mathrm{O}}₆$ ($x\ensuremath{\approx}0.23$) thin films. We found that in spite of the nonstoichiometry, Co is in a divalent state while Mn ions show a mixed valence state. The relation of this finding with the magnetic properties of the films is discussed. X-ray magnetic circular dichroism measurements prove that magnetic anisotropy originates from Co spin-orbit coupling and it is strain dependent: a strong increase of the angular contribution to the magnetic moment is found when in-plane (out-of-plane) cell parameters get expanded (compressed). This behavior is reproduced by first order perturbation theory calculations.