| X-ray magnetic circular dichroism (XMCD) spectroscopy is a relatively new spectroscopy technique, which allows the quantitative measurement of magnetic moments. The main strengths of this technique are the independent determination of the spin and orbital magnetic moments and the elemental specificity. Two experiments have been performed on transition metal thin films (namely Co and Fe) which underscore the strength of this spectroscopy method.; In the first XMCD experiment, the anisotropy in the orbital magnetic moment was quantified in an ultrathin Co film in a Au/Co/Au system to support the theoretical calculation proposed by Bruno. Bruno has predicted a quantitative relationship between the orbital anisotropy and magnetocrystalline anisotropy energy, based on spin-orbit interaction in ferromagnetic transition metal elements. In the second experiment, the elemental magnetic moments of Ni, Fe and Cu were measured in a Ni/Fe/Cu/Pt system. The XMCD results have shown that, as the Fe thickness varies from 0 to 35 Angstroms, the crystalline structure varies from FCC to FCC{dollar}spprime{dollar} to BCC, which has a dramatic effect on the magnetization of Fe; the Fe is ferromagnetic for thicknesses under 3 monolayers (ML), loses its magnetization at around 5 ML, and then becomes ferromagnetic again for thickness above 7 ML, corresponding to the crystallographic changes.; The two experiments display the strength of XMCD method, and show that XMCD spectroscopy is an extremely powerful tool in analyzing complex magnetic thin film structures. |
