The large change in electromagnetic impedance in ferromagnetic state of softmagnetic metals in presence of biasing magnetic field is associated with changein screening of electromagnetic field. The screening depends on thepermeability of the metal. Apart from dependence on intrinsic properties ofmetal the permeability depends on size of the sample. It is observed that thedecrease in MI in amorphous ferromagnetic ribbon of Fe40Ni40B20 alloy is largefor long sample whereas corresponding change is small for short one with samebiasing field. As intrinsic magnetic properties and bias field are same and thedemagnetization factor increases with reduction of length of the sample thereduction of MI effect is associated with demagnetization field.
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