(Fe65Co35)83.5-xB13NbxSi2Cu1.5 amorphous ribbons with (4 at.%) and without (0 at.%) growth inhibitor Nb were Joule annealed at low current intensity to avoid bulk crystallization, and their surface domain structure, bulk and surface magnetization, and high frequency magneto-impedance (MI) were systematically investigated. Magneto-optic Kerr effect (MOKE) microscopy and longitudinal MOKE evidenced the development of a longitudinal surface anisotropy in the ribbon without Nb (Nb0) as a result of the Joule annealing treatment, while the 4 at.% Nb (Nb4) ribbon developed an anisotropy 30° from the transverse direction. The increased transverse ac permeability at the surface of Nb4 was evident in MI measurements by a higher [ΔZ/Z]max as compared to Nb0 at frequencies greater than 200 MHz. A correlation between the surface domain structure, induced anisotropy and high frequency MI in the ribbons was established.
Eggers, T., Leary, A., McHenry, M., Marcin, J., Škorvánek, I., Srikanth, H., & Phan, M. H. (2016). Correlation between domain structure, surface anisotropy and high frequency magneto-impedance in Joule annealed CoFe-based melt-spun ribbons. Journal of Alloys and Compounds, 682, 799–804. https://doi.org/10.1016/j.jallcom.2016.04.312