Variation of magnetization and the Lande g factor with thickness in Ni-Fe films

We have measured the Lande g factor, the effective magnetization M-eff, the uniaxial anisotropy H-k, and the Gilbert damping parameter alpha, as a function of Permalloy film thickness from 2.5 to 50 nm. We used a pulsed inductive microwave magnetometer capable of generating dc bias fields of 35.2 kA/m (440 Oe). A significant decrease in g is observed with decreasing thickness below 10 nm. Also, Meff decreases with decreasing thickness consistent with a surface anisotropy constant of 0.196+/-0.025 mJ/m(2). The decrease in g can arise from the orbital motion of the electrons at the interface not being quenched by the crystal field. We also compare our data to a model of an effective g factor suggesting that the decrease in g factor might also stem from the Ni-Fe interface with a Ta underlayer.