Ultra-stable Co-based metallic glassy microwires for highly sensitive giant-magnetoimpedance sensors

The development and deployment of giant magnetoimpedance (GMI) sensors have been significantly hampered by their limited sensitivity to weak magnetic fields and pronounced thermal drift phenomena, both of which are intricately linked to the microstructural properties of the sensor core material, typically composed of metallic glass microwires (MGMWs). Herein, we successfully fabricated an ultra-stable Co-based MGMW with a high GMI effect through a novel multi-step stress-Joule coupled annealing (MS-JCA) technique. The Co-based MGMW showcases a significantly improved GMI effect with an unprecedented impedance change rate of 939%, coupled with an enhanced magnetic field sensitivity of 734%/Oe. In addition, the MS-JCA process ensures the GMI sensor retains exceptional stability during thermal drift measurements over a span of 20 h, characterized by a minimal signal fluctuation ratio of merely 0.59%. Notably, the ultra-stability of the GMI sensor arises from the ultra-stable energy state of the MGMWs following MS-JCA. Our findings offer a compelling strategy for significantly enhancing both the performance and stability of GMI sensors, thereby establishing a solid technical foundation for their broader application in weak magnetic detection.