Asymmetric Magneto-Impedance in CoFeSiB Amorphous Microwire

The symmetric dependences of magneto-impedance on the applied longitudinal dc magnetic field were measured in an amorphous CoFeSiB microwire. Additional application of a circumferential dc bias magnetic field was used to achieve the asymmetric magneto-impedance in the microwire. The obtained results are theoretically interpreted taking into account the cylindrical core-shell magnetic structure and the helical anisotropy induced during the microwire preparation. The observed very steep linear magneto-impedance dependences crossing H = 0 are promising for technical applications of the CoFeSiB microwire as a sensor of low magnetic fields.