1Hitachi Research Laboratory, Hitachi Ltd., Hitachi
Eddy current in magnetic material give rise to energy loss. For thin tape, theoretical analysis show that the eddy current loss is proportional to the frequency of a.c. field (f) and square of thickness of tape (d2). On ultrathin Mo-permalloy core, hysteresis loop was measured at frequency ranging from 1 Kc/s to 70 Kc/s. For magnetic tape thinner than 10 μ , the energy loss is greater than that predicted by the d2f low.
On the ultrathin permalloy, the eddy current loss is greater, being due to the localized movement of domain wall. Examining of a.c. hysteresis loop at high frequency leads to an classifying of kinetics of domain reversal for thickness of the tape of thin permalloy material.
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