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Studies of temperature dependence of the Giant magnetoimpedance, GMI, effect become essentially relevant from the viewpoint of applications of magnetic wire inclusions embedded in multifunctional composite materials for non-destructive and non-contact stress and temperature monitoring [1]. Most of the few studies on temperature dependence of GMI were performed in thick amorphous wires without glass coating and in very limited temperature range [2]. Although the highest GMI effect is usually observed in Co-rich magnetic microwires, GMI effect of Fe-rich glass-coated microwires can be substantially improved by stress-annealing induced magnetic anisotropy [3].
We studied the temperature dependence of the magnetic properties and giant magnetoimpedance, GMI, effect in Co$_{69.2}$Fe$_{3.6}$Ni$_{1}$B$_{12.5}$Si$_{11}$Mo$_{1.5}$C$_{1.2}$ and Fe$_{75}$B$_{9}$Si$_{12}$C$_{4}$ glass-coated microwires, with nearly-zero and positive magnetostriction coefficient, respectively. The amorphous glass coated microwires were produced by the Taylor Ulitovsky technique and measured in as-prepared and annealed states. Remarkable change in the hysteresis loops and GMI effect is observed for both samples upon heating. Co$_{69.2}$Fe$_{3.6}$Ni$_{1}$B$_{12.5}$Si$_{11}$Mo$_{1.5}$C$_{1.2}$ microwires present a modification in the hysteresis loop shape upon heating that correlates with a change in the $\Delta Z/Z(H)$ dependencies. In as-prepared and most of the heat treated samples the hysteresis loop transformation from inclined to squared upon heating correlates with the change in $\Delta Z/Z(H)$ dependencies from double-peak to single-peak. However, the stress-annealed at 118 MPa samples present better thermal stability of the $\Delta Z/Z(H)$ dependencies and hysteresis loops. In all the studied samples an increase in the GMI ratio at 300 $^{\circ}$C was observed.
For as-prepared FeBSiC microwire a beneficial influence of the temperature on the GMI ratio is observed and hysteresis loops change of character from almost rectangular shape to inclined one. On the other hand, although GMI ratio improvement after stress-annealing (annealing temperature Tann= 325 $^{\circ}$C, stress applied during the annealing $\sigma$= 190MPa) decreases with the temperature increasing, temperature dependence can be tuned by the stress annealing conditions. Additionally, almost complete reversibility of the changes induced by the temperature is observed. The origin of the observed temperature dependences is discussed in terms of the Hopkinson effect, temperature dependence and relaxation of internal stresses, induced magnetic anisotropy, and temperature dependence of the magnetostriction coefficient.
References
[1] V. Zhukova et al., “Free Space Microwave Sensing of Carbon Fiber Composites With Ferromagnetic Microwire Inclusions,” IEEE Sensors Letters, vol. 8, no. 1. Institute of Electrical and Electronics Engineers (IEEE), pp. 1–4, Jan. 2024. doi: 10.1109/lsens.2023.3337071.
[2] J. Nabias, A. Asfour, and J.-P. Yonnet, “Temperature Dependence of Giant Magnetoimpedance in Amorphous Microwires for Sensor Application,” IEEE Transactions on Magnetics, vol. 53, no. 4. Institute of Electrical and Electronics Engineers (IEEE), pp. 1–5, Apr. 2017. doi: 10.1109/tmag.2016.2625841.
[3] P. Corte-Leon, V. Zhukova, J. M. Blanco, L. González-Legarreta, M. Ipatov, and A. Zhukov, “Stress-induced magnetic anisotropy enabling engineering of magnetic softness of Fe-rich amorphous microwires,” Journal of Magnetism and Magnetic Materials, vol. 510. Elsevier BV, p. 166939, Sep. 2020. doi: 10.1016/j.jmmm.2020.166939.
