Temperature Dependence of Magnetization Reversal and Harmonic Spectrum in Low Curie Temperature Amorphous Microwires

The present study focuses on the investigation of the magnetization reversal process in amorphous microwires of the composition Co64.82Fe3.9B10.2Si12Cr9Mo0.08, which possesses a low Curie temperature TCof 61°C. The microwire retains a nearly rectangular hysteresis loop, an axial anisotropy and a positive magnetostriction up to TC. The coercivity decreases with temperature, following the decrease in the saturation magnetization MS, but it has a different dependence on MSfar from and near TC, which suggests different mechanisms of magnetostriction in these temperature intervals. Furthermore, the harmonic spectrum of the voltage induced during remagnetization is also temperature sensitive. The area under the voltage pulse is directly proportional to MS, resulting in a comparable dependence of the harmonic amplitudes. In the context of potential applications in wireless temperature sensors, measuring the harmonic spectrum offers distinct advantages based on lock-in techniques. In addition, the temperature range over which the harmonic spectrum varies most is extended by using two (or potentially few) microwires with different TC. The change in TCfrom 61°C to 57°C is achieved by current annealing of the same microwire, which helps to extend the temperaturesensitive range of the two microwire harmonic response between 40°C and 61°C.