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Author Murayama, A. ♦ Hyomi, K. ♦ Eickmann, J. ♦ Falco, C. M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ COBALT ♦ FERROMAGNETIC MATERIALS ♦ GOLD ♦ COPPER ♦ SPIN WAVES ♦ MAGNETO-OPTICAL EFFECTS ♦ COERCIVE FORCE ♦ THIN FILMS ♦ THICKNESS ♦ ANISOTROPY ♦ BRILLOUIN EFFECT ♦ MAGNETIC PROPERTIES ♦ KERR EFFECT ♦ HYSTERESIS ♦ MAGNETIZATION
Abstract We have used spin-wave Brillouin scattering to study the perpendicular magnetic anisotropy of ultrathin Co/Au/Cu(111) films with various thicknesses of Au underlayer. From the field dependence of the spin-wave frequency we find that the second-order (fourth power) uniaxial perpendicular anisotropy increases monotonically with increasing Au-underlayer thickness ranging from 0 to 5 monolayers (ML), while the first-order (second power) anisotropy shows a nonmonotonic increase with a minimum at 1 ML Au. The ratio of the second-order anisotropy constant to the first one also increases with increasing Au thickness, from 0.01 to 0.07. We observe saturation for both the perpendicular anisotropy constants for a 5 ML Au underlayer, which coincides with saturation of expansion of the in-plane Co lattice due to the coherent growth of Co at the interface between the Co and Au underlayer. When the thickness of Au is further increased beyond 5 ML, we find an anisotropy-independent increase in coercivity on the polar-Kerr hysteresis curves. We also have observed a field-dependent broadening of the spin-wave Brillouin spectrum around a critical field between out-of-plane and in-plane magnetizations, which we explain by assuming a distribution of the first-order perpendicular anisotropy. As the result, the normalized distribution of the first-order anisotropy is shown to have a minimum at 1 ML Au thickness. We believe the observed Au-thickness dependences of the perpendicular anisotropy and of the distribution are characteristic behaviors due to an atomic-scale transition of the underlayer materials from Cu to Au. {copyright} {ital 1998} {ital The American Physical Society}
ISSN 01631829
Educational Use Research
Learning Resource Type Article
Publisher Date 1998-10-01
Publisher Place United States
Journal Physical Review, B: Condensed Matter
Volume Number 58
Issue Number 13


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