Enhanced giant magneto-impedance effect in soft ferromagnetic amorphous ribbons with pulsed laser deposition of cobalt ferrite

We have grown a 50 nm thick magnetic layer of cobalt ferrite (CFO) on two Co-based amorphous ribbons of compositions Co65Fe4Ni2Si15B14 (type I) and Co69Fe4Ni1Mo2B12Si12 (type II) by a pulsed laser deposition technique. A comparative study of the influence of this CFO layer on the giant magneto-impedance (GMI) effect and field sensitivity (η) of the ribbons is presented. Our results reveal that the presence of the CFO layer enhanced both the GMI ratio and the field sensitivity of the ribbons. Relative to the plain ribbons, the GMI ratio and field sensitivity of the CFO-coated ribbons increased by 97% and 42% for type I and by 34% and 50% for type II, respectively. The enhanced effects are attributed to the modifications on the ribbon surface and closure of magnetic flux paths due to the CFO layer.