Enhanced magnetoimpedance in CoP electrodeposited microtubes

Studies of magnetic properties, magnetoimpedance and magnetic force microscopy on electrodeposited CoP magnetic microtubes are presented. The electrodeposited CoP is a heterogeneous material consisting of non-magnetic wires, which are electrode posited with magnetic layers of amorphous CoP of several micrometers in thickness. This material has been reported to exhibit gaint magneto-impedance (GMI) up to high magnetic fields (tens of kA/m) with only a small hysteresis at low fields (typically tenths of kA/m). The aim of this work has been to enhance the GMI sensitivity of such microtubes by means of a proper annealing. Results show a GMI increase of about 270%. with respect to the as-deposited state. after an annealing at 473K/1h. These results are explained considering the change of anisotropy of the magnetic layer after annealing. (C) 2001 Elsevier Science B.V. All rights reserved.