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 Co20.77Ni61.74Fe17.49, Co18.21Ni41.20Fe40.59, Co18.97Ni49.60Fe31.43, Co46.01Ni39.87Fe14.12 or Co33.67Ni51.44Fe14.89. 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 Co18.97Ni49.60Fe31.43 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.