Structure and magnetic properties of Sm-Co(x nm)/Co (6 nm) multi-layered nanocomposite films

A detailed analysis of the structures and magnetic properties has been made for ten-layered films of [Sm-Co(x nm)/Co(6 nm)]. By studying the dependences of the coercivity on annealing temperature (T-alpha) and time (t(alpha)) for the various films, we deduced an optimal heat-treatment with a T-alpha about 570 degreesC and t(alpha) of about 20 min. Applying a magnetic field during annealing was harmful to the coercivity due to a reduction in the number of domain wall pinning sites and to grain coarsening. With decreasing thickness of the Sm-Co layer, the dependence of the coercivity on the applied field became less pronounced. The Henkel plot, deltam, of the-multilayered films showed the comparative magnitudes of exchange interaction for quite different coercivity values, and suggested that the increase in the coercivity might be due to improving the, pinning effectiveness, not to enhancement of the exchange coupling. Magnetic viscosity measurements indicated that a lower switching field corresponded to a larger coercivity due to more effective pinning of the domain walls.