Brillouin light scattering of CoFe/IrMn based top and bottom spin valves

Abstract

Magnetic anisotropy fields of CoFe/IrMn-based permalloy films having bottom and top spin-valve structures were studied by Brillouin light scattering (BLS). The spin-valves were deposited by high vacuum dc magnetron sputtering at room temperature. The magnetoresistance ratio of the bottom spin-valve (BSV) and top spin-valve (TSV) reaches 7.3 % and 9.1 % at room temperature, respectively. The exchange bias field of the BSV and TSV are 232 and 273 Oe, respectively. BLS was then employed to study the spin-wave dispersion as a function of both the applied magnetic field and the wave vector direction on the surface plane. The frequencies of the surface spin waves were analyzed using an approach expression proposed by J. F. Cochran et. al. The results demonstrated that the BSV holds strong out-of plane anisotropy whereas for the TSV in-plane anisotropy is dominant.