Giant magnetoimpedance effect in CuBe/NiFeB and CuBe/insulator/NiFeB electroless-deposited composite wires

The giant magnetoimpedance (GMI) effect of CuBe/NiFeB and CuBe/insulator/NiFeB composite wires prepared by electroless-deposition was investigated. The results showed that geometry dimension has a significant influence on the GMI effect of CuBe/NiFeB composite wire. As the NiFeB layer thickness approaches the skin depth of the NiFeB layer, maximum GMI will be expected; it reaches -23% at 1 MHz. After adding an insulator layer, the GMI ratios of CuBe/insulator/NiFeB composite wire were much higher than those of CuBe/NiFeB composite wire. The maximum GMI ratio of CuBe/insulator/NiFeB composite wire was 250% at 500 kHz-1 MHz. This result is related to current redistribution under the external magnetic field and the electromagnetic interaction between the conductive core and the ferromagnetic layer, and also is related to the skin effect and eddy current of the sample.