Fabrication and magnetic characteristics of hybrid double walled nanotube of ferromagnetic nickel encapsulated conducting polypyrrole

This letter is a report on hybrid double walled nanotubes (HDWNTs) of crystalline ferromagnetic nickel (Ni) nanotubes encapsulated conducting polypyrrole (PPy) nanotubes through a sequentially electrochemical synthetic method. Ferromagnetic Ni nanotubes were fabricated by an electrochemical deposition method outside the wall of the conducting PPy nanotubes. The formation and structure of HDWNTs of conducting PPy nanotubes and ferromagnetic Ni nanotubes were confirmed by transmission electron microscopy, high-resolution transmission electron microscopy, and elementary analysis. From the angular dependences of the magnetic hysteresis curves of the HDWNTs, the authors observed that the Ni nanotubes of the HDWNT systems had an anisotropic ferromagnetic nature with the maximum of coercivity and remanent-saturation magnetization when applying a magnetic field along the parallel direction of the tubes.