Barkhausen Jump Amorphous Ribbon Sensor by Means of Inducing Herical Anisotropy

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Depending on the remarkable controlability of magnetic properties in amorphous materials, an effort was made successfully to fabricate the Barkhausen jump sensor elements by means of introducing the domain wall pinning caused by the locally induced herical anisotropy. The Barkhausen jump sensor element can generate the sharp pulse voltage in windings, then can be applied to reliable rotary encorder sensor and directional sensor without power supply. The research results are summarized as follows,(1) The herical anisotropy can be easily induced by annealing into the region where the domain wall exists during annealing. This region works as nucleation sites of reverse domain and pinning centers of domain walls and the re-entrant properties can be available.(2) The pinning force introduced even in short annealing time is fairly large, so that the reverse domain nucleates at the ribbon ends and grows abruptly to participates in the flux jump. Consequently, the jitter of pulse voltage (-do/dt) is large. To improve that precise control of wall pinning force is needed.(3) The wall width of amorphous materials is as wide as 2mu m, and increases with the induced herical anisotropy to increase the anisotropy energy in the wall which makes balance with the exchange energy.