Giant magneto-impedance and magneto-inductive effects in amorphous alloys (invited)
Abstract
Recent experiments have discovered giant and sensitive magneto-impedance and magneto-inductive effects in FeCoSiB amorphous wires. These effects include a sensitive change in an ac wire voltage with the application of a small dc longitudinal magnetic field. At low frequencies (1-10 kHz) the inductive voltage drops by 50% for a field of 2 Oe (25%/Oe) reflecting a strong field dependence of the circumferential permeability. At higher frequencies (0.1-10 MHz) when the skin effect is essential, the amplitude of the total wire voltage decreases by 40%-60% for fields of 3-10 Oe (about 10%/Oe). These effects exhibit no hysteresis for the variation of an applied field and can be obtained even in wires of 1 mm length and a few micrometer diameter. These characteristics are very useful to constitute a highly sensitive microsensor head to detect local fields of the order of 10-5 Oe. In this paper, we review recently obtained experimental results on magneto-inductive and magneto-impedance effects and present a detailed discussion for their mechanism, developing a general approach in terms of ac complex impedance in a magnetic conductor. In the case of a strong skin effect the total wire impedance depends on the circumferential permeability through the penetration depth, resulting in the giant magneto-impedance effect.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- November 1994
- DOI:
- 10.1063/1.358310
- Bibcode:
- 1994JAP....76.6198P
- Keywords:
-
- Amorphous Materials;
- Boron;
- Cobalt;
- Impedance;
- Iron;
- Magnetic Induction;
- Magnetoelectric Media;
- Silicon;
- Wire;
- Electric Potential;
- Impedance Measurement;
- Magnetic Fields;
- Magnetic Permeability;
- Magnetic Probes;
- Solid-State Physics