Demagnetisation effect and its correction on the measurement of magnetic hysteresis loop of melt-spun ribbons

Demagnetisation field arising from the free poles at the ribbon ends makes the measurement of hysteresis loop inaccurate for melt-spun high permeability ribbon shaped sample. No standard equation is also available for calculation of demagnetisation factor for such samples. In the present paper, attempts have been made to use empirical relations for demagnetisation correction of ribbon shaped FeNbCuSiB based material having thickness of the order of 35 μm. To the first approximation the material was considered as a cylinder with the equivalent cross-sectional area of the ribbon. A pre-factor, φ, was multiplied with the demagnetisation factor for equivalent cylindrical specimen to get the corrected demagnetisation factor of the measured sample. φ=0.65 was found to be the optimum pre-factor for the demagnetisation corrected hysteresis loop.