【摘要】 提出了由中间为高电导率的非铁磁性金属丝外面包裹一层铁磁材料组成的复合结构丝的电流密度分布和巨磁阻抗(GMI)效应模型,并对Cu/FeCoNi复合丝进行了数值模拟.结果表明:在相同的磁性材料几何尺寸和磁特性时,Cu/FeCoNi复合丝铁磁层内的电流随频率的升高比匀质FeCoNi铁磁丝内的电流更趋于表面分布,而且开始出现趋肤效应时对应的频率明显降低.当在比较低的频率下就可以观察到明显的MI变化时,复合结构丝中的电阻和电抗变化主要是由趋肤效应引起,趋肤效应仍然是引起复合结构材料(包括多层薄膜结构)产生GMI效应的重要原因.当频率升高到4MHz以上时,驱动电流将主要从Cu/FeCoNi复合结构丝的FeCoNi铁磁层流过,中间的Cu对铁磁层的电磁作用减弱,复合结构丝的MI行为逐渐类似于匀质铁磁丝的MI行为.更多还原

【Abstract】 The current-density distribution and giant magnetoimpedance (GMI) properties are theoretically described for the homogenous ferromagnetic wires and composite wires consisting of an inner conductive core covered by an outer ferromagnetic coating. The numerical simulation shows that the current is distributed much closer to the surface for the Cu/FeCoNi composite wires than for FeCoNi homogenous ferromagnetic wires at the same frequency and with the same geometric size and magnetic structure. When obvious MI effect can be observed, the skin effect has already been strong in its ferromagnetic coating. The skin effect is still an important factor for the GMI effect in composite wires. Above a certain frequency of about 4?MHz, the driving current will flow through the ferromagnetic coating mainly and the electromagnetic interactions become weaker, the MI behavior in the composite wire becomes similar to that in the homogenous ferromagnetic wire.更多还原