Magnetic behavior of exchange-coupled Fe30Au70/Fe65Au35 bilayers -: art. no. 094402

The evolution of magnetic configurations inside ferromagnetic Fe30Au70/Fe65Au35 bilayers have been studied. The two FeAu alloys magnetization are ferromagnetically exchange coupled at the interface and both exhibit an in-plane uniaxial anisotropy. The magnetization reversal of a bilayer from one saturated state to the other occurs via an interface domain wall state, which is metastable. This interface magnetic domain wall which spreads mainly in the soft Fe30Au70 layer is pinned at the interface by the harder Fe65Au35 alloy. Its presence and its "compression" are evidenced by magnetization, electrical transport, and ac-susceptibility measurements combined with a unidimensional micromagnetic calculation. In order to investigate magnetization reversal dynamics, temperature dependence as well as magnetic aftereffect measurements were performed. The magnetization reversal process is found to be thermally activated and activation parameters could be deduced.