Fabrication Of Complex Wires With Structure Of Coaxial Cable By Electrochemical Method And Study Of GMI Effect

Complex wires with Giant Magnetic Impedance(GMI)effect have been produced by electrodepositing soft magnetic alloy coating over cylindrical Cu substrates. Complex wires deposited with CoP alloy are CoP-Cu complex wires and that deposited with FeNi alloy are FeNi-Cu complex wires.It has been studied the influence of CoP and FeNi soft magnetic alloy relative content and basic magnetism with electrodeposition technics conditions. The dependence of GMI of two group of CoP-Cu,FeNi-Cu complex wires on content in deposits has been tested and the relationship of soft magnetism and GMI effect was compared. It is found that soft magnetism is better, GMI radio is greater. GMI effect of complex wires are very great, best of all is Co88.5P11.5-Cu complex wire which GMI radio is 441%,best of magnetic field sensitive degree is 0.2%/(A/m)(about16.5%/Oe).It has particularly been investigated the dependence of GMI effect on DC magnetic field. There are two sorts of dependences,â‘ GMI radio increases slightly to a peak and then decreases to saturated value with increasing of DC magnetic field;â‘¡GMI radio decreases monotonously to saturation.It has been studied that The AC frequency spectrum of GMI in detail. The experimental results show that GMI effect of the complex-structure sample has lower characteristic frequency and wider work frequency range which are of importance for technological applications. Complex wire is provided with bigger GMI ratio when the amplitude of AC current flowing through it is greater, but when DC magnetic field is over some field intensity, GMI ratio don't depend on amplitude of AC current, GMI effect has no change when adding a DC bias current below 20 mA. In addition, one group of samples with different magnetic shell thickness and same Cu wire diameter and the other group of samples with different Cu wire diameter and same magnetic shell thickness have been prepared respectively to investigate the influence of structure to GMI effect. It is found that the magnetic shell is thicker or Cu wire diameter is bigger, the GMI effect is stronger as well as the characteristic frequency is lower.Lastly, based on the boundary condition directly connecting of magnetic shell and conducting core and redistributing of AC current in complex wire with structure of coaxial cable, electromagnetic model is given. The impedance expression of complex wire is educed by equation Maxwell and equation Landau-Lifshitz-Gilbert. Results show that GMI of complex wire has been enhanced because of its structure of coaxial cable and the conductivity of core is greater, the GMI effect is more obvious. It is also analyzed numerically in detail that an optimum ratio of radius of core and thickness of shell is beneficial to the improvement of the GMI effect for a complex wire whose whole radius is fixed.