DOMAIN-WALL RESONANCE IN EXCHANGE-COUPLED MAGNETIC-FILMS

Exchange coupling between magnetic films in multilayer geometries can strongly influence magnetization behavior and spin-wave energies by co rrelating the motion of spins in one film with the motion of spins in adjacent films. In a similar fashion correlations can be expected betw een domain walls existing in neighboring exchange coupled films. In th is paper we show that the motion of domain walls in neighboring films can depend strongly on interfilm exchange coupling. A static equilibri um configuration exists for the domain walls, and small amplitude osci llations about equilibrium can result in domain-wall resonances that i nvolve interfilm exchange energies. Frequencies for optic- and acousti c-type domain-wall resonances are calculated and effects of a small st atic applied magnetic field are examined, revealing distinctly differe nt behaviors for the acoustic and optic domain-wall resonances. The po ssibility for sensitive measurements of the local coupling by studying domain-wall resonance is discussed. Resonances with parallel and anti parallel coupling are considered and the response to a small in-plane driving field is calculated.