
Magnetic vortices and solitons are prominent examples of topologically
nontrivial structures. We study the
dynamics of topological magnetic solitons
in two and threedimensional ferromagnets.
The framework is the LandauLifshitz equation.
The surprising dynamics of vortices and solitons in ferromagnets
are understood only through the direct link of dynamics
in magnets to the topology of the magnetisation configurations
[see, e.g.,
Phys. Rev. Lett. 99, 117202 (2007)].
Our studies are both fieldtheoretical and numerical
(using our "micromagnetics" code).
Our work on antiferromagnets
includes a derivation of a continuum model (the nonlinear σmodel)
and the discovery that a direct link between magnetisation topology
and antiforromagnetic vortex dynamics
is induced by the presence of an external field as this breaks
the Lorentz invariance of the system
[
Nonlinearity 11, 265290 (1998)].
You may be also interested in more rigorous mathematical work which
was motivated by the above results
(see
"Static Theory for Planar Ferromagnets and Antiferromagnets")
For spiral antiferromagnets
we discuss the spiral state, the spinflop state, but we also
predict the existence of an intermediate phase, in between these two
[
Phys. Rev. B 65, 064433 (2002)].
The current intensive experimental activity
on mesoscopic ferromagnetic elements
has opened promising directions for applications of magnetic materials
as well as for theoretical work on the mesoscopic and nanoscopic level.
In collaboration with the
Thin Film Magnehtism (TFM) Group
(head Professor J.A.C. Bland) at the Cavendish Laboratory, Cambridge
we have extended ideas about topological magnetic
solitons to the case of mesoscopic (submicron) magnetic elements.
Magnetic bubbles (Skyrmions)
exist and have been observed
in perpendicular anisotropy ferromagnetic nanostructures
of FePt alloy
[see, e.g.,
Phys. Rev. B 74, 214406 (2006), and
Phys. Rev. B 76, 104426 (2007),
or the PhD Thesis
currently carried out in Cambridge].
Our work is linked in the
Virtual Journal of Nanoscale Science & Technology,
and it is reviewed in the
Nanotechnology Website of the Institute of Physics.
Our current project is on magnetisation dynamics in three dimensional
systems with a major focus on
freely propagating structures in ferromagnetic nanowires.
Selected presentations of this work
[Talk on "vortices and bubbles in nanodots" at the MMM, 10/1/2007, Baltimore
(pdf)]
[Poster on "rotating vortex dipoles", 22/5/2007, Dresden
(pdf)]
[Poster on "Transmutation of momentum into position in magnetic vortices" at the Intermag, 8/5/2008, Madrid
(pdf)]
[Review article on
"Dynamics of vortex pairs in ferromagnets"].
