https://doi.org/10.1140/epjb/e2008-00255-1
Magnetic ordering in (110) Eu films in an applied magnetic field
1
Laboratoire de Physique des Matériaux, Université H. Poincaré-Nancy I, BP 239, 54506 Vandoeuvre-les-Nancy Cedex, France
2
Universidade Federal do Rio de Janeiro, Instituto de Física, 21945-970 Rio de Janeiro, RJ, Brazil
3
LLB, CEA Saclay, 91191 Gif-sur-Yvette, France
Corresponding author: a dufour@lpm.u-nancy.fr
Received:
22
October
2007
Revised:
10
April
2008
Published online:
10
July
2008
Below its ordering temperature (TN = 90 K), bulk bcc Eu has a helical
magnetic state with propagation vectors along the three equivalent 〈100〉
directions. In contrast, epitaxial (110)Eu films exhibit a unique magnetic
ordering : the domain with a magnetic helix propagating along the in-plane
[001] direction vanishes on cooling, at the expense of other domains with
helices propagating along [100] and [010]. This paper is devoted to the
study of the stability of the magnetic domains in an external magnetic field
using neutron scattering experiments and macroscopic magnetization
measurements. The helix propagating along the [001] direction can be
restored by the application of an external field along this direction. On
the contrary, when a magnetic field is applied along an intermediate
direction, specifically , the domain with a helix
propagating along [001] is suppressed. Both effects depend on the film
thickness. They are explained if one considers that, because of the low
magnetic anisotropy of Eu, a helix with a propagation vector parallel to (or
close to) the applied magnetic field is energetically more favourable than
cycloidal structures with unchanged propagation vectors. Finally, the
amplitudes of the propagation vectors and their directions (that are
modified in films compared to bulk) do not vary under magnetic field.
PACS: 75.25.+z – Spin arrangements in magnetically ordered materials / 75.70.Ak – Magnetic properties of monolayers and thin films / 68.55.-a – Thin film structure and morphology / 61.12.Ex – Neutron scattering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008