Processing of magnetic properties of nearly zero magnetostrictive glass-coated microwires by current annealing

The effect of dc current annealing (with length up to 80 min and current density j up to 250 A/mm/sup 2/), with or without dc axial magnetic field, on the magnetic properties of Co/sub 55.7/Fe/sub 5.9/Ni/sub 9.9/B/sub 17.7/Si/sub 10.8/ and Co/sub 68/Mn/sub 7/Si/sub 10/B/sub 15/ glass-coated microwires has been studied. Such thermal treatments, especially performed under magnetic field, modify the magnetic parameters, such as coercivity, remanent magnetization, magnetic permeability, and overall shape of the hysteresis loops. Such phenomenology can be interpreted by considering the noticeable longitudinal magnetic anisotropy induced by the combined effects of the magnetic field and internal stresses arising from the coating during the thermal treatment.