Low Frequency Giant Magneto-Impedance Effect of Co-Rich Ribbons Induced by Joule Annealing Treatment

The giant magneto-impedance (GMI) effect of Co83.2Fe5.2Si8.8B2.8 ribbons at frequencies <1 MHz was analyzed. To improve the GMI response, a Joule annealing treatment conducted with direct current, and domain structure ribbon surface investigated via magneto-optical Kerr microscopy. annealed show larger impedance changes under external magnetic fields, higher field sensitivity is obtained by certain current treatments. 418 782%/(kA/m) 0.2 0.8 are achieved after A for 20 min. electric induces stress relaxation, rearrangement, crystallization process gradually increases increasing density, which gives rise to anisotropic reformation. release stresses due heating below temperature causes homogenous distribution induced rapid solidification influences elastic anisotropy, causing structures become much more regular. crystallization, along precipitation hard phases, crystal anisotropy intense coupling action. Consequently, domains in rearranged reformed heat transverse current. irregular domains, complex as-cast corresponding weak transformed into regular strip-like easy magnetization 0.4 A. After A, further fine axial fingerprint-like sensitive change field, allowing best response. These results indicate that an optional method optimize soft properties these Co-rich low frequencies.