Abstract
The influence of Joule heating on magnetic properties, giant magnetoimpedance (GMI) effect and domain wall (DW) dynamics of Fe75B9Si12C4 glass-coated microwires was studied. A remarkable (up to an order of magnitude) increase in GMI ratio is observed in Joule heated samples in the frequency range from 10 MHz to 1 GHz. In particular, an increase in GMI ratio, from 10% up to 140% at 200 MHz is observed in Joule heated samples. Hysteresis loops of annealed samples maintain a rectangular shape, while a slight decrease in coercivity from 93 A/m to 77 A/m, after treatment, is observed. On the other hand, a modification of MOKE hysteresis loops is observed upon Joule heating. Additionally, an improvement in DW dynamics after Joule heating is documented, achieving DW propagation velocities of up to 700 m/s. GMI ratio improvement along with the change in MOKE loops and DW dynamics improvement have been discussed considering magnetic anisotropy induced by Oersted magnetic fields in the surface layer during Joule heating and internal stress relaxation. A substantial GMI ratio improvement observed in Fe-rich Joule-heated microwires with a rectangular hysteresis loop and fast DW propagation, together with the fact that Fe is a more common and less expensive metal than Co, make them suitable for use in magnetic sensors.
Highlights
Soft magnetic materials play an increasing role in various technological applications [1–5].One of the most relevant applications of soft magnetic materials involves the development of high performance magnetic sensors, magnetometers and devices [2–8]
We have continued their study with the aim to evaluate the influence of Joule heating on magnetic properties, giant magnetoimpedance (GMI) effect and domain wall dynamics and compare with the same properties of as-prepared, annealed and stress-annealed
Rectangular hysteresis loops are observed in as-prepared and even Joule heated microwires, while a tendency towards a slight decrease in the coercivity, Hc, can be seen, the maximum decrease being from 93 to 77 A/m for the sample annealed with I = 10 mA. Such hysteresis loops are typical for Fe-rich microwires with high and positive λs
Summary
Soft magnetic materials play an increasing role in various technological applications [1–5]. One of the most relevant applications of soft magnetic materials involves the development of high performance magnetic sensors, magnetometers and devices [2–8]. A combination of magnetic softness with good physical properties (mechanical properties, corrosion resistance, biocompatibility) and low cost are other relevant features for industrial applications [9–12]. Amorphous materials prepared by rapid melt quenching can present one of the most favorable combinations of excellent magnetic softness together with good mechanical, corrosion properties and variable geometry [3–14]. These properties of amorphous materials are intrinsically related to their glassy-like structure. The main route for λs tuning is determined by the appropriate selection of the chemical composition [15]: vanishing λs -values can be obtained either in Co-rich amorphous materials in Co1−x Fex or Cox Mn1−x systems for 0.03 ≤ x ≤ 0.08 or in Ni- rich
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