Interlayer dipolar interactions in multilayered granular films

Abstract

Using the ferromagnetic resonance (FMR) technique, the interlayer coupling is studied in granular multilayered system (CoFe∕Al2O3)n with varying number of layers n=1,…,8. The main difference between the cases of n=1 and n⩾3 is a notable splitting of FMR line under external field normal to layers. This is explained by an interlayer dipolar coupling, only possible for discontinuous layers. The relative magnitudes of two absorption peaks and distance between them are described by a simple model of planar square lattices of magnetic dipoles.