84,150 research outputs found
East is East?:understanding aspects of Indian culture(s) within organisations: a special issue of Culture and Organization Volume 21, issue 5 (2015)
A model for structural defects in nanomagnets
A model for describing structural pointlike defects in nanoscaled
ferromagnetic materials is presented. Its details are explicitly developed
whenever interacting with a vortex-like state comprised in a thin nanodisk.
Among others, our model yields results for the vortex equilibrium position
under the influence of several defects along with an external magnetic field in
good qualitative agreement with experiments. We also discuss how such defects
may affect the vortex motion, like its gyrotropic oscillation and dynamical
polarization reversal.Comment: 8 pages, resubmitted to Journal of Applied Physic
How hole defects modify vortex dynamics in ferromagnetic nanodisks
Defects introduced in ferromagnetic nanodisks may deeply affect the structure
and dynamics of stable vortex-like magnetization. Here, analytical techniques
are used for studying, among other dynamical aspects, how a small cylindrical
cavity modify the oscillatory modes of the vortex. For instance, we have
realized that if the vortex is nucleated out from the hole its gyrotropic
frequencies are shifted below. Modifications become even more pronounced when
the vortex core is partially or completely captured by the hole. In these
cases, the gyrovector can be partially or completely suppressed, so that the
associated frequencies increase considerably, say, from some times to several
powers. Possible relevance of our results for understanding other aspects of
vortex dynamics in the presence of cavities and/or structural defects are also
discussed.Comment: 9 pages, 4 page
Three-point correlators from string amplitudes: Mixing and Regge spins
This paper has two parts. We first compute the leading contribution to the
strong-coupling mixing between the Konishi operator and a double-trace operator
composed of chiral primaries by using flat-space vertex operators for the
string-duals of the operators. We then compute the three-point functions for
protected or unprotected scalar operators with higher spin operators on the
leading Regge trajectory. Here we see that the nontrivial spatial structures
required by conformal invariance arise naturally from the form of the
polarization tensors in the vertex operators. We find agreement with recent
results extracted from Mellin amplitudes for four-point functions, as well as
with earlier supergravity calculations. We also obtain some new results for
other combinations of operators.Comment: v3: corrected numerical factor and other minor change
Adittional levels between Landau bands due to vacancies in graphene: towards a defect engineering
We describe the effects of vacancies on the electronic properties of a
graphene sheet in the presence of a perpendicular magnetic field: from a single
defect to an organized vacancy lattice. An isolated vacancy is the minimal
possible inner edge, showing an antidotlike behaviour, which results in an
extra level between consecutive Landau levels. Two close vacancies may couple
to each other, forming a vacancy molecule tuned by the magnetic field. We show
that a vacancy lattice introduce an extra band in between Landau levels with
localization properties that could lead to extra Hall resistance plateaus.Comment: 6 pages, 4 figures, few comments added after referees - accepted to
publication in Phys. Rev.
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