Hysteresis in Asymmetrical GMI Effect in Amorphous Microwires

J. Kravčák Department of Physics, Faculty of Electrical Engineering and Informatics, Technical University of Košice, Park Komenského 2, 042 00 Košice, Slovakia

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The double-peak behaviour of giant magneto-impedance (GMI) dependence on the external magnetic field strength H is observed in as-cast glass-covered amorphous thin wire Co70.5Fe4.5Si15B10 (microwire), as well as in microwire with the removed glass cover. The position of sharp peaks is symmetrical (H=± Hm) with respect to zero external magnetic field strength (H=0) and corresponds to the critical field of irreversible magnetization rotation. The maximum GMI ratio (Δ Z/Z)max dependence on the amplitude of current iac at frequency of 1 MHz is analysed by means of the helical anisotropy (0<α<90°), induced during preparation of the microwire and after glass-cover removing. The additional dc bias current idc ≤ iac is applied in order to achieve asymmetrical GMI effect. Asymmetrical GMI dependences exhibit hysteresis which can be explained by irreversible magnetization rotation at ferromagnetic surface of the microwire.

DOI: 10.12693/APhysPolA.126.132 PACS numbers: 75.30.Gw, 75.50.Kj, 75.60.Ej