Enhanced magnetoimpedance effect in Co-based amorphous ribbons coated with carbon nanotubes

We report upon the enhancement of the giant magnetoimpedance (GMI) effect in Co-based amorphous ribbons coated with non-magnetic carbon nanotubes (CNTs). In our study, the CNTs were drop-casted onto the surface of a Metglas (R) 2714 A ribbon with three different concentrations (5, 10, and 15 mu L of CNTs). Relative to the plain ribbon, a 15% enhancement of the GMI effect was observed in the ribbon coated with 10 mu L of CNTs. The GMI effect first increased with the CNT concentration, to a maximum of 10 mu L of CNTs, and then decreased at higher concentrations. Noticeably, at a measured frequency of 10 MHz, the magnetic field-induced ac resistance change was about 35% larger for the ribbon coated with 10 mu L of CNTs than for the plain ribbon. These observations may reveal a new perspective for developing CNT-based gas sensors that operate using the principle of the GMI effect. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676214]