Domain-induced anomaly of the spin-wave frequency in perpendicular magnetized Ni(001) thin films

Epitaxial Cu/Ni/Cu/Si~001! magnetic films have been studied in the thickness range ~17-120 Å! where a uniaxial anisotropy favoring the direction perpendicular to the film plane is dominant over the easy-plane dipolar interaction. Using magneto-optic magnetometry and Brillouin light scattering we show that on decreasing an in-plane magnetic field the perpendicular component of the magnetization breaks into domains