Giant magneto-impedance effect in as-cast and post-production treated Fe77.5Si7.5B15 amorphous wires

Abstract

Giant magneto impedance (GMI) effect is investigated on as-cast and post-production treated highly positive magnetostriction Fe77.5Si7.5B15 amorphous wire with the diameter of 125 mu m and 12 cm long. As-cast, furnace annealed, furnace annealed under axial tension, dc current annealed, and furnace annealed under transverse magnetic field samples were prepared for this investigation. The highest GMI ratio was found to be around 6 MHz for all samples except current annealed sample. The domain structure and wall mechanism are responsible for this behaviour. The circumferential field is less pronounced in the annealed sample under transverse magnetic field than the as-cast sample due to its anisotropy. Also, the skin effect becomes more dominant in the post-production treated samples at higher frequencies. It is found to be the GMI effect sensitively depends on the post-production treated process, induced anisotropy, and domain structures.