Abstract
Effects of current annealing on magnetic hysteresis properties and magnetoimpedance (MI) of glass-coated amorphous microwires with nominal composition of Co71Fe5B11Si10Cr3 and small positive magnetostriction were investigated with the purpose to control the magnetic anisotropy. We have demonstrated that current annealing can produce a controllable change in the easy anisotropy direction from almost axial to circular, depending on the annealing time. The induced magnetization configuration is very sensitive to the applied tensile stress. The combination of positive magnetostriction and helical anisotropy makes it possible to realise large stress-magnetoimpedance (S-MI) effect without use of any dc bias fields owing to the directional change in magnetization. This is especially important for microwave frequency S-MI effect and can be very interesting for developing stress-sensors operating at the high frequency region.
Highlights
A considerable interest has been devoted to studying the magnetization processes and magnetoimpedance (MI) in Co-Fe based amorphous glass-coated microwires, which is related to their technical applications in miniature sensor devices [1,2,3,4]
We report on the influence of dc current annealing on the magnetic anisotropy in Co-rich amorphous microwires having a small positive magnetostriction
We have demonstrated that the current annealing produces a controllable change in the easy anisotropy direction from almost axial to helical accompanied by corresponding changes in the magnetic hysteresis and MI
Summary
A considerable interest has been devoted to studying the magnetization processes and magnetoimpedance (MI) in Co-Fe based amorphous glass-coated microwires (diameter is between 1 to 100 μm), which is related to their technical applications in miniature sensor devices [1,2,3,4]. Co-Fe alloys on Co-rich side possess a near-zero magnetostriction and excellent soft magnetic properties In these systems, it is possible to control the magnetic anisotropy by current annealing which combines the Joule heating and circular magnetic field [10,11,12]. The induced helical anisotropy increases the relative change in impedance (MI ratio) up to 200% (from 10% in as-prepared state) in the lowfield region, but makes it possible to realize highly stresssensitive MI. This has a potential for applications in miniature stress sensors, in particular, for embedded sensing techniques [13,14,15]
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