Magnetization-reversal mechanism of hard/soft exchange-coupled trilayers -art. no. 174415

Ni80Fe20/Sm40Fe60/Ni80Fe20 trilayers with in-plane uniaxial anisotropy indu ced by an applied magnetic field during deposition were prepared on (100)-S i substrates by de magnetron sputtering. Magnetization hysteresis loops wer e measured by an alternating-gradient magnetometer for various angles betwe en the external magnetic field and the easy axis. The experimental hysteres is loops were quantitatively described by a theoretical model that combines coherent rotation and domain-wall unpinning. When the external field is al ong the easy axis, the magnetization reversal is caused by domain-wall unpi nning. When the external field is along or near the hard axis, the magnetiz ation reversal is caused by coherent rotation. For other orientations, the magnetization first rotates gradually by coherent rotation and then sharply switches by domain-wall unpinning. The domain-wall angle and the pinning e nergy at the Sharp switching strongly depend on the angle between the exter nal field and the easy axis. Furthermore, the dependence of the coercivity measured in the easy direction on the thickness of Ni80Fe20 layers was theo retically reproduced by an extended model of domain-wall unpinning.