Magnetic properties of ferromagnetic nanowires embedded in nanoporous alumina membranes

• Published in: Journal of magnetism and magnetic materials 2002-08, Vol.249 (1), p.241-245
• Main Authors: Kröll, M, Blau, W.J, Grandjean, D, Benfield, R.E, Luis, F, Paulus, P.M, de Jongh, L.J
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystallographic structure; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Magnetic anisotropy; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetically ordered materials: other intrinsic properties; Magnetisation reversal; Magnetization curves, hysteresis, Barkhausen and related effects; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Nanowires; Physics
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(02)00537-1

Iron, nickel and cobalt nanowires are prepared within the pores of nanoporous alumina membranes using an electrochemical AC plating procedure. Nanowires produced in this way can be easily varied in diameter (5–250 nm) and length (up to several hundred microns). The magnetisation curves for these nanowire/alumina composites can then be determined not only as a function of the temperature but also as a function of the wire diameter and length. Conclusions regarding the magnetisation reversal processes that take place in the wires can be drawn. For Fe and Ni nanowires, we show that the magnetisation process in wires with a diameter smaller than the domain wall width is independent of the wire length and probably takes place via the formation of a small magnetic domain at the end of the wires and a subsequent propagation of the domain wall along the wire. For Co nanowires a competition between the shape anisotropy and the temperature- and size-dependent magnetocrystalline anisotropy could be observed.