Document 
Eur. Phys. J. B 20, 35-54
Magnetic anisotropy and domain patterns in electrodeposited cobalt nanowires
Y. Henry1, K. Ounadjela1, L. Piraux2, S. Dubois3, J.-M. George4 and J.-L. Duvail51 Institut de Physique et Chimie des Matériaux de Strasbourg (CNRS UMR 7504) and Université Louis Pasteur, 23 rue du Loess, 67037 Strasbourg Cedex, France
2 Département des Sciences des Matériaux et des Procédés, Université Catholique de Louvain, Place Croix du Sud 1, Louvain la Neuve 1348, Belgium
3 Laboratoire de Métallurgie Physique (CNRS UMR 6630) and Université de Poitiers, 86960 Futuroscope Cedex, France
4 Laboratoire Central de Recherches Thomson (CNRS/Thomson-CSF UMR 137) , Domaine de Corbeville, 91404 Orsay, France
5 Institut des Matériaux de Nantes (CNRS UMR 6502) and Université de Nantes, 2 rue de la Houssinière, 44322 Nantes Cedex 03, France
yves.henry@ipcms.u-strasbg.fr
(Received 14 September 2000)
Abstract
The magnetic anisotropy and domain structure of electrodeposited cylindrical
Co nanowires with length of 10 or 20 
m and diameters ranging from 30
to 450 nm are studied by means of magnetization and magnetic torque
measurements, as well as magnetic force microscopy. Experimental results
reveal that crystal anisotropy either concurs with shape anisotropy in
maintaining the Co magnetization aligned along the wire or favours an
orientation of the magnetization perpendicular to the wire, hence competing
with shape anisotropy, depending on whether the diameter of the wires is
smaller or larger than a critical diameter of 50 nm. This change of crystal
anisotropy, originating in changes in the crystallographic structure of Co,
is naturally found to strongly modify the zero (or small) field magnetic
domain structure in the nanowires. Except for nanowires with parallel-to-wire
crystal anisotropy (very small diameters) where single-domain behaviour may
occur, the formation of magnetic domains is required to explain the
experimental observations. The geometrical restriction imposed on the
magnetization by the small lateral size of the wires proves to play an
important role in the domain structures formed.
75.50.-y - Studies of specific magnetic materials.
75.30.Gw - Magnetic anisotropy.
75.60.Ch - Domain walls and domain structure.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001