Magnetic coupling in multilayer ferromagnetic film structures

Indirect exchange coupling through magnetic bridges and magnetostatic coupling attributed to dipole-dipole interaction were observed in multilayer ferromagnetic film structures. This multilayer film consisted of an ordinary NiFe film with a normal uniaxial anisotropy, a thin separation layer of chromium and gold, and an anomalous NiFe film with a pronounced rotatable remanent magnetization. Both types of coupling produced a bias field and thus caused asymmetric magnetic properties of the ordinary film. It was also found that the effective coercive force of the ordinary film was greatly influenced by the interaction between domain walls and the stray field of the surface pole distribution. Generally, it increased as a result of the coupling and decreased exponentially as the thickness of the separation layer increased. Because of the presence of the magnetic coupling between the magnetizations and the interaction between normal walls and the stray field of the surface pole distribution, the coercive force of the ordinary film was found to be magnetically alterable by changing the remanent magnetization direction of the anomalous film.