26 research outputs found
Bound-states and polarized charged zero modes in three-dimensional topological insulators induced by a magnetic vortex
By coating a three-dimensional topological insulator (TI) with a
ferromagnetic film supporting an in-plane magnetic vortex, one breaks the
time-reversal symmetry (TRS) without generating a mass gap. It rather yields
electronic states bound to the vortex center which have different probabilities
associated with each spin mode. In addition, its associate current (around the
vortex center) is partially polarized with an energy gap separating the most
excited bound state from the scattered ones. Charged zero-modes also appear as
fully polarized modes localized near the vortex center. From the magnetic point
of view, the observation of such a special current in a TI-magnet sandwich
comes about as an alternative technique for detecting magnetic vortices in
magnetic thin films.Comment: 8 pages, 3 figures, new version with more discussions and results
accepted for publication in The European Physical Journal
Remarks on Charged Vortices in the Maxwell-Chern-Simons Model
We study vortex-like configuration in Maxwell-Chern-Simons Electrodynamics.
Attention is paid to the similarity it shares with the Nielsen-Olesen solutions
at large distances. A magnetic symmetry between a point-like and an
azimuthal-like current in this framework is also pointed out. Furthermore, we
address the issue of a neutral and spinless particle interacting with a charged
vortex, and obtain that the Aharonov-Casher-type phase depends upon mass and
distance parameters.Comment: New refs. added. Version accepted for publication in Phys. Lett.
Huyghens Principle, Planck Law: Peculiarities in the Behavior of Planar Photons
Huyghens principle and Planck law are studied in Maxwell and
Maxwell-Chern-Simons frameworks in (2+1) dimensions. Contrary to (3+1)
dimensions, massless photons are shown to violate Huyghens principle in planar
world. In addition, we obtain that Planck law is no longer proportional to
, but to the squared frequency, , of the planar photons. We also
briefly discuss possible physical consequences of these results.Comment: 10 pages, no figures. Latex forma
On Phase Transition and Vortex Stability in the Generalized XY Models
We study a recent generalization proposed for the XY model in two and three
dimensions. Using both, the continuum limit and discrete lattice, we obtained
the vortex configuration and shown that out-of-plane vortex solutions are
deeply jeopardized whenever the parameter of generalization, , is increased.
The critical temperature for such models is calculated using the self
consistent harmonic approximation. In both, two- and three-dimensional cases,
such a temperature decreases with raising . Our results are also compared
with other approximated methods available in the literature.Comment: 7 pages, 1 figur
Magnetic vortex-like excitations on a sphere
We study magnetic vortex-like solutions lying on the spherical surface. The
simplest cylindrically symmetric vortex presents two cores (instead of one,
like in open surfaces) with same charge, so repealing each other. However, the
net vorticity is computed to vanish in accordance with Gauss theorem. We also
address the problem of a flat plane in which a conical, a pseudospherical and a
hemispherical segments were incorporated. In this case, if we allow the vortex
to move without appreciable deformation in this support, then it is attracted
by the conical apex and by the pseudosphere as well, while it is repealed by
the hemisphere. This suggests that such surfaces could be viewed as pinning and
depinning geometries for those excitations. Spherical harmonics coreless
solutions are discussed within some details.Comment: 15 pages, 8 .eps figures, typed in tex. Version accepted in Physics
Letters A (2007), please see DOI