A novel ferromagnetic/semiconductor oxide nanocomposite formed by arrays of Ni
nanocylinders grown by the electrodeposition technique in a semiconductor oxide matrix of
self-aligned and randomly disordered titanium dioxide nanotubes has been synthesized.
X-ray diffraction, EDX, SEM, AFM, rf-GDOES and VSM magnetometry techniques
have been used to investigate the structural, compositional and morphological
properties, as well as its specific magnetic behaviour. Titania nanotubes have been
grown through a single anodization process, by using HF acidic electrolytes in a
potentiostatic mode. The thus-obtained titanium dioxide nanotube outer diameter ranges
between 90 and 150 nm, wall thickness about 25–40 nm and 300 nm in depth. The
electrodeposited Ni nanocylinders reach above 100 nm diameter and 240 nm length,
giving rise to coercive fields of 98 and 200 Oe, well within the hysteresis loops
perpendicular or parallel to the nanocylinder axis, respectively, which could be
ascribed to the formation of magnetic vortex domain states. It is expected that this
novelty nanocomposite, based on ferromagnetic Ni nanocylinders embedded in a
semiconductor titanium dioxide nanotube template, will become a promising candidate for
many applications in a broad range of scientific and technological areas, such
as ultrahigh density magnetic storage media or spin-based electronic devices.