Length effect in a Co-rich amorphous wire

Abstract

The effect of the sample length on the magnetization process of a Co-rich amorphous wire has been experimentally and theoretically studied in this paper. Experimentally it is found that the spontaneous magnetic bistability observed in a Co-rich wire is lost if the sample becomes shorter than some critical length. Such critical length is smaller than that one of Fe-rich wire. Besides, the remanent magnetization of a wire with the length less than the critical length is an increasing function of the wire length. Theoretical explanation of the observed behavior suggests that the magnetization of the inner core of the Co-rich amorphous wire, normally directed along the wire axis, may be twisted near the wire ends due to the demagnetizing field. As a result, the longitudinal component of the wire magnetization reduces gradually towards the wire ends. It is shown that the characteristic critical length for the reduction of the longitudinal magnetization component can be several orders larger than the wire radius. This estimation is in qualitative agreement with the experimental data.