High frequency permeability of thin film magnetic core.

Nishioka, K.; Mitsuoka, K.; Aihara, Makoto; Narishige, S.; Sugita, Y.

doi:10.3379/jmsjmag.13.327

Cited by 4 publications

(3 citation statements)

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“…[6]), the material's hysteresis loop typically increases in area and the amount of shearing with increasing frequency. Such dynamic hysteresis loops, recently measured in a closed flux configuration [7] at up to 20 MHz, indeed showed a large increase in power dissipation (as indicated by the hysteresis loop area) with increasing frequency. While such losses are to be expected due to eddy currents induced in the metal core, it appears that additional loss mechanisms, detected in a thin-film head by a surface-sensitive magneto-optic technique [8], degrade the high frequency writing performance even further.…”

Section: Introductionsupporting

confidence: 53%

“…4, this approach to saturation is difficult to ascertain precisely from a measurement of just a few low-order harmonics. For such a measurement, it may be necessary to use a wide-bandwidth oscilloscope [7] or a modulation technique designed to measure the differential susceptibility [13].…”

Section: Discussionmentioning

confidence: 99%

“…To understand how the material would perform in a thin-film head, it is necessary to measure the large-signal "permeability" as the relevant parameter for the inductive head writing. Such measurements have been carried out recently [3][4][5] at fields large enough to observe significant non-linear phenomena.…”

Section: Introductionmentioning

confidence: 99%

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On the Possibility of Hysteresis Loop Reconstruction From High Frequency Waveforms

1991

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A parallelogram-shaped hysteresis loop is chosen to represent the flux response of a material subjected to sinusoidally varying magnetic field excitation. For excitation frequencies exceeding 100 MHz, a precise measurement of the loop shape is often impractical because of the limited bandwidth and accuracy of the measuring instruments. To simulate the effect of low-pass filtering, Fourier coefficients are computed analytically and a hysteresis loop is then reconstructed from one or more of the lowest-order harmonics. The analysis shows that it is sufficient to measure just a few harmonics to obtain an excellent approximation of the exact hysteresis loop shape. Measurement of the harmonic content of the response by means of a spectrum analyzer is suggested for determining how many harmonics are needed to achieve a desired precision in the hysteresis loop shape. We also emphasize that for purely sinusoidal excitation, power dissipation is given directly, regardless of the hysteresis loop shape, by just the quadrature at the fundamental frequency component of the response waveform. Thus dissipation mechanisms which degrade the permeance at high frequency and at large flux-amplitude can be conveniently measured with a network analyzer.

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Section: Introductionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 99%