The magnetic properties of ultrathin FeBNbCu nanocrystalline alloy

The magnetic properties of ultrathin Fe/sub 83/B/sub 9/Nb/sub 7/Cu/sub 1/ nanocrystalline alloy ribbons with 7/spl sim/12 /spl mu/m thickness and the effects of insulation coating on ultrathin ribbons were investigated. It was found that the effective permeability at a frequency below 100 kHz decreased and the coercive force increased with decreasing ribbon thickness. However, reduction of ribbon thickness to 7 /spl mu/m was very effective in improving remarkably the permeability and the core loss characteristics up to the MHz frequency range. Furthermore, the soft magnetic properties were largely enhanced by surface coating compared to that of the uncoated ribbons. From the results, we could produce new core materials with very low magnetic loss applicable to MHz excitations.