ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The critical magnetic field Hcr for the Barkhausen effect of ferromagnetic amorphous alloys can be modified and reduced by applying ac high-frequency magnetic fields. Both straight and toroidal specimens of amorphous ribbons Fe78B13Si9 (Allied 2605S2) and Fe40Ni38Mo4B18 (Allied 2826MB) were used in our experiment. The waveforms of ac magnetic fields were sine, triangular, or square waves, and the directions of the applied ac magnetic field were either parallel or perpendicular to the length direction of the specimen. For as-cast Fe78B13Si9, applying ac magnetic fields of 100 Hz–1 kHz and magnitudes 0.1–0.3 Oe, the critical magnetic field of the specimen could be reduced from 0.075 to 0.02 Oe under the same exciting field and magnetic induction. For as-cast Fe40Ni38Mo4B18, applying ac magnetic field of 100 Hz–1 kHz and magnitudes 0.1–0.3 Oe, could reduce the Hcr from 0.06 to ≤0.01 Oe under the same exciting field and magnetic induction. If the specimens were heat treated first by ac Joule heating and then applying the same ac magnetic fields when measuring the B-H curves, the critical magnetic fields could be reduced to lower than 0.001 Oe under the same exciting magnetic field and magnetic induction. By using a suitable frequency and magnitude of the ac magnetic field, we observed a magnetic behavior similar to superparamagnetism (i.e., coercive force Hc=0).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.345894
