MAGNETIC AND STRUCTURAL-X-RAY DICHROISMS OF METALLIC MULTILAYERS

Fe/Cu and Co/Cu multilayers are intensively studied because of their e xceptional magnetic properties, i.e., their giant magnetoresistance an d the oscillations of the magnetic coupling between magnetic layers as a function of the thickness of the copper spacer [S.S. Parkin et al., Phys. Rev. Lett. 66 (1991) 2152; F. Petroff et al., Phys. Rev. B 44 ( 1991) 5355]. Spectroscopic approaches to the understanding of the coup ling of ferromagnetic layers through a noble metal layer have been rec ently introduced, in particular spin-resolved photoemission [N.B. Broo kes et al., Phys. Rev. Lett. 67 (1991) 354; C. Carbone et al., PRL 71 (1993) 2805] inverse photoemission [J.E. Ortega et al., Phys. Rev. Let t. 69 (1992) 844; Phys. Rev. B 47 (1993) 1540] and magnetic circular d ichroism [S. Pizzini et al., MRS Symp. Proc., vol. 313 (1993); M.G. Sa mant et al. Phys. Rev. Lett. 72 (1994) 2152; S. Pizzini et al., Phys. Rev. Lett. 74 (1995) 1470]. X-ray absorption spectroscopy appears to b e effective both for determination of the local structure, specific to the bidimensionality of the system but also for the electron symmetry -dependent evaluation of the spin polarisation of the noble metal as w ell as the magnetic element.