AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+TF-FrM

Paper MI+TF-FrM3
Lande g-factor Variation with Thickness in Ultrathin Permalloy Films

Friday, November 8, 2002, 9:00 am, Room C-205

Session: Magnetic Thin Films and Surfaces
Presenter: J.P. Nibarger, National Institute for Standards and Technology
Authors: J.P. Nibarger, National Institute for Standards and Technology
R. Lopusnik, National Institute for Standards and Technology
T.J. Silva, National Institute for Standards and Technology
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We have found a variation in the Lande g-factor with thickness in sputtered polycrystalline Permalloy films capped with Cu. The variation of the g-factor is correlated with damping in the absence of an applied bias field. Films were grown on a sapphire substrate with a 5 nm Ta adhesion layer, followed by 10, 25, 50, or 100 nm of NiFe, and finally capped with a 5 nm layer of Cu. Static anisotropy values were obtained using a static inductive magnetometer and the effective saturation magnetization was found using an alternating gradient magnetometer. A pulsed inductive microwave magnetometer (PIMM) was used to extract dynamical information.@footnote 1@ Using the static values and the Kittel equation for thin films, we extracted the induced uniaxial anisotropy, the Lande g-factor, and the Landau-Lifshitz phenomenological damping parameter, @alpha@, from the PIMM measurements. The g-factor increases with decreasing thickness for films below 50 nm, as does also the damping in zero applied field. In addition, the effective saturation magnetization decreases with decreasing thickness, presumably due to surface anisotropy effects. The increase in the g-factor is interpreted as an indicator of enhanced spin-orbit coupling for thinner films: As the films become thinner and thinner, the relative magnitude of the spin-orbit coupling at interfaces becomes dominant. We will discuss the role of spin-orbit in damping by conduction electron scattering, as well as implications for the transport of spin angular momentum in nano-scale magnetic heterostructures. @FootnoteText@ @footnote 1@ T. J. Silva, C. S. Lee, T. M. Crawford, C. T. Rogers, J. Appl. Phys. 85, 7849 (1999)