Exchange bias behaviour of amorphous CoFeNiSiB ribbons

摘要

A dramatic exchange bias behaviour was found in superior soft Co58Fe5NiloSi11 B 16amorphous ribbons with proper thermomagnetic annealing conditions. This characteristic,which was directly obtained at room temperature, is quite different from that of the traditionalferromagnetic—antiferromagnetic system. The observation of microstructure indicated that thematrix of the annealed ribbons with the exchange bias behaviour includes a few crystallinephases. The magnetic domains of the ribbon surface were scanned to clarify the configurationof local magnetic moments. A subsequent magnetic torque measurement revealed thatunidirectional magnetic anisotropy was induced in the amorphous ribbons with a longitudinalfield. The obtained evidence supports our point of view that the local crystalline phases in theribbons along with the longitudinal thermomagnetic treatment are the key factors in promotingthe formation of an exchange bias. A simple phenomenological discussion was developed toexpound this interesting behaviour in ribbons.