Super-giant Magneto-Impedance Effect of a LC-resonator Using a Glass-Coated Amorphous Microwire

Abstract

A new discovery of the super-giant magneto-impedance (SGMI) effect was found out in a LC-resonator consisted of a glass-coated amorphous Co_(83.2)B_(3.3)Si_(5.9)Mn_(7.6) microwire. The measurement was carried out at high frequency range from 100 ㎒ up to 1 ㎓ of an ac-current flowing along the wire and at varying axial dc-magnetic field in its range of ±120 Oe. The wires, about 16 ㎛ in diameter, were fabricated by a glass-coated melt spinning technique. The shape of the impedance curves plotted vs. a dc-field is changing dramatically with the frequency. The phase angle was also strongly dependent on this field. The external dc-magnetic field changes the circumferential permeability as well as the penetration depth, both in turn change the impedance of the sample. The drastic increments of SGMI at high frequency can be understood in terms of the LC-resonance phenomena. The sudden change of the phase angle, as large as 180°, evidenced the occurrence of the resonance at a given intensity of the external dc-field. The maximum ratio of SGMI reached in the experiment by precise tuning frequency equals 450,000% at the frequency of around 551.9075 ㎒.