Noise characteristics of Co-based amorphous tapes to be applied as magnetic shielding shell for magnetic shaking

In order to seek a magnetic shell material of low magnetic noise under magnetic shaking, fluctuations of the magnetization under the 1 kHz excitation are characterized and compared to the Barkhausen noise (BHN) under the sine-current excitation of 2 Hz. Two Co-based amorphous magnetic tapes, Metglas 2705M and 2714A, are examined. Measurements were carried out in a cylindrical magnetic shield with two identical toroidal samples to cancel the fundamental component and harmonics of the excitation voltage. Induced voltages in the frequency range less than 500 Hz were considered as fluctuation noise. A good correlation between fluctuation noise and BHN was confirmed for both samples. Metglas 2705M has high shaking efficiency but higher noise than Metglas 2714A.