Magnetooptical spectroscopy of magnetic multilayers: Theory and experiment(A review)

Experimental and theoretical results on the optical and magnetooptical (MO) spectral properties of a series of Co/Cu, Co/Pd, Co/Pt and Fe/Au multilaye rs are reviewed. Diagonal and off-diagonal components of the optical conduc tivity tensor have been determined in the photon energy range 0.8-5.5 eV fr om the polar and longitudinal Kerr rotation as well as ellipticity and elli psometry measurements. The conductivity tensor has been evaluated on the ba sis of self-consistent spin-polarized relativistic linear muffin-tin orbita l (LMTO) band-structure calculations within the local spin-density approxim ation. The role of the spin polarization and the spin-orbit interaction in the formation of the magnetooptical Kerr effect (MOKE) spectra as inferred from first-principles calculations is examined and discussed. The high sens itivity of the MO properties to the interface structure is studied by ab in itio modeling of the effects of the interfacial alloying, substitutional di sorder, and the roughness at the interfaces. It is shown that the MOKE spec tra of the multilayered structures (MLS) calculated using the LMTO method r eproduce the experimental spectra only moderately well if ideal MLS with sh arp interfaces are assumed. It is shown that the MOKE spectra of the MLS ca n be adequately reproduced only by taking into account their real interface microstructure. The magnetooptical anisotropy (MOA) is studied both experi mentally and theoretically for a series of Fe-n/Au-n superlattices prepared by molecular beam epitaxy with n=1,2,3 Fe and Au atomic planes of (001) or ientation. The results of the LMTO calculations show that the microscopic o rigin of the large MOA is the interplay of the strong spin-orbit coupling o n Au sites and the large exchange splitting on Fe sites via Aud-Fe d hybrid ization of the electronic states at the interfaces. The orientation anisotr opy of the d orbital moment is calculated from first principles and analyze d on the basis of d orbital symmetry considerations. The relationship betwe en the orbital moment anisotropy and the MOA is discussed. The reviewed res ults imply that the magnetooptical properties of multilayers with various c ompositions and structures can be quantitatively predicted from first-princ iples band-structure calculations. Such a possibility is important for basi c research as well as applications. (C) 2001 American Institute of Physics.