Electronic structure and magnetic properties of Al-doped Fe_3O_4 films studied by x-ray absorption and magnetic circular dichroism

摘要

The electronic structure and magnetic properties of Al-doped Fe_3O_4 films at various Al concentrations were investigated by Al and O K-edge x-ray absorption near-edge structure (XANES) and Fe L_(3,2)-edge magnetic circular dichroism (MCD) measurements. The O K-edge XANES spectra reveal that the intensity of O 2p-Fe 3d hybridized states decreases linearly as the Al concentration increases, suggesting that nonmagnetic Al substitution reduces couplings of the O 2p with Fe 3d orbitals. The Fe L_3-edge MCD spectra show that the intensities of MCD features decrease as the Al concentration increases, which suggests that Al substitution reduces the magnetic moments of Fe ions. The Fe L_(3,2) XANES spectra suggest the absence of mixed valence states in agreement with previous x-ray resonance scattering measurements.