Giant magnetoimpedance effect in electroplated CoNiFe/Cu wires with varying Ni, Fe and Co content

Giant magnetoimpedance (GMI) behaviour has been studied for wires consisting of an 8.82–13.75 μm thick magnetic layer containing either Co_20.77Ni_61.74Fe_17.49, Co_18.21Ni_41.20Fe_40.59, Co_18.97Ni_49.60Fe_31.43, Co_46.01Ni_39.87Fe_14.12 or Co_33.67Ni_51.44Fe_14.89. These magnetic layers were electroplated onto a 50 μm diameter Cu non-magnetic wire. A large and sensitive GMI effect (about a 257% magnetoimpedance ratio) with nearly no hysteresis has been found in Co_18.97Ni_49.60Fe_31.43 wire at a 90 kHz ac driving current. Scanning electron microscopy (SEM) images showed that samples have globular and crack-free deposits with a grain size that varies between 3.06 and 9.17 μm.