Magnetic coupling in Fe/sub 60/Sm/sub 40/-Fe/sub 95/Ta/sub 5/N multilayers

Three sets of exchange spring magnetic films and multilayers with different characteristics and well-defined uniaxial anisotropy have been studied by magnetization and ferromagnetic resonance (FMR) techniques. It was found that the exchange spring behavior is strongly influenced by the thickness of the individual layers. In FMR measurements, two or more modes can be observed. These modes are related only to the soft phase and the different resonance fields arise from the different anisotropy of the soft layers. It was also observed that the effective demagnetization field is larger in multilayers than in single films, suggesting the presence of an additional easy plane anisotropy.