Anisotropic susceptibilities of thin ferromagnetic films within many‐body Green's function theory

Transverse and parallel static susceptibilities of in-plane uniaxial anisotropic ferromagnetic films are calculated using a Heisenberg model within the framework of many-body Green's function theory. The importance of collective magnetic excitations, in particular in the paramagnetic regime, is demonstrated by comparing with mean field calculations. The paper extends the work of Jensen et al. [1] on the monolayer with spin 1/2 to the multilayer case with arbitrary spin. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)