Fabrication of vertically aligned carbon nanotubes for spintronic device applications

Abstract

We report on the observation of coulomb blockade and coulomb staircase at room temperature in multiwalled carbon nanotube (MWCNT) based heterostructures. The hybrid structure consists of nickel ferromagnets separated by vertically aligned MWCNTs. The MWCNTs were grown vertically on a nickel substrate by a double plasma hot filament chemical vapour deposition technique. Deposition of ferromagnetic nickel nanoparticles on the top of MWCNTs was achieved for the first time using the laser chemical vapour deposition method. The fabrication technique is unique in that it is formed of many individual ferromagnetic tunnel junctions integrated into a single system. A well defined coulomb blockade and coulomb staircase was displayed in current–voltage characteristics obtained by scanning tunnelling spectroscopy. The capacitance (1. 6 × 10⁻¹⁸ F) in the system is determined from the spacing ΔV between peaks in the dI/dV curves.