Enhanced magnetoimpedance in CoP electrodeposited microtubes

Studies of magnetic properties, magnetoimpedance and magnetic force microsc opy on electrodeposited CoP magnetic microtubes are presented. The electrod eposited CoP is a heterogeneous material consisting of non-magnetic wires, which are electrode posited with magnetic layers of amorphous CoP of severa l micrometers in thickness. This material has been reported to exhibit gain t magneto-impedance (GMI) up to high magnetic fields (tens of kA/m) with on ly 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 mea ns of a proper annealing. Results show a GMI increase of about 270%. with r espect to the as-deposited state. after an annealing at 473K/1h. These resu lts are explained considering the change of anisotropy of the magnetic laye r after annealing. (C) 2001 Elsevier Science B.V. All rights reserved.