Exchange-spring systems: Coupling of hard and soft ferromagnets as measured by magnetization and Brillouin light scattering (invited)

An experimental and theoretical study is presented of the normal magnetic modes in spiral ferromagnetic structures. The bilayer system studied consists of Fe layers (25, 50, 100, and 200 Å thick) that are exchange coupled to 200 Å thick SmCo films that have ≈200 kOe anisotropies. The Fe spiral - induced by an external magnetic field that is applied opposite to the direction of the magnetized film - results in a structure similar to that encountered in a Bloch domain wall. The magnetization and the field dependence of the magnons in various Fe films are explained by the theoretical model. © 1999 American Institute of Physics.