Studies Of Giant Magneto-Impedance Effect In Fe-based Nanocrystalline Ribbons

It is called Giant Magneto Impedance Effect that the alternating impedance of magnetic materials takes on quickly respond, alternation with high sensitivity under external magnetic fields. The studies recently demeonstrate that Fe-based nanocrystalline ribbons which have been produced through annealed with magnetic field or stress have characteristic Giant Magneto Impedance Effect.This thesis studies Giant Magneto Impedance Effect in Fe-based nanocrystalline ribbons. Considering the model of a one axial film, according to classical Maxwell system of equations and the principle of conservation of energy, through theoretical derivation, we reach the magneto impedance's expression under high frequency and low frequency. Under high frequency, we investigate the relation of betweem the Fe-based nanocrystalline ribbons' permeability, external magnetic field and induced anisotropy field. Under low frequency, we analyse the impact of internal stress and environment DC field versus stuff permeability. The results are as follows: Fe-based nanocrystalline ribbons have more remarkable Giant Magneto Impedance Effect under high-frequency compared with low-frequency; Giant Magneto Impedance Effect with high-frequency reaches to the maximum at the point of external direct-current magnetic fields(approximately equals to induced anisotropy field). It can be useful to improve the Giant Magneto Impedance Effect ratio of materials through reducing induced anisotropy field which are induced by anneal, or reducing the magnetic conductive of beginning.