393 research outputs found
Characteristic molecular properties of one-electron double quantum rings under magnetic fields
The molecular states of conduction electrons in laterally coupled quantum
rings are investigated theoretically. The states are shown to have a distinct
magnetic field dependence, which gives rise to periodic fluctuations of the
tunnel splitting and ring angular momentum in the vicinity of the ground state
crossings. The origin of these effects can be traced back to the Aharonov-Bohm
oscillations of the energy levels, along with the quantum mechanical tunneling
between the rings. We propose a setup using double quantum rings which shows
that Aharonov-Bohm effects can be observed even if the net magnetic flux
trapped by the carriers is zero.Comment: 16 pages (iopart format), 10 figures, accepted in J.Phys.Cond.Mat
Dielectric confinement of excitons in type-I and type-II semiconductor nanorods
We theoretically study the effect of the dielectric environment on the
exciton ground state of CdSe and CdTe/CdSe/CdTe nanorods. We show that
insulating environments enhance the exciton recombination rate and blueshift
the emission peak by tens of meV. These effects are particularly pronounced for
type-II nanorods. In these structures, the dielectric confinement may even
modify the spatial distribution of electron and hole charges. A critical
electric field is required to separate electrons from holes, whose value
increases with the insulating strength of the surroundings.Comment: Journal of Physics: Condensed Matter (in press
Electronic structure of few-electron concentric double quantum rings
The ground state structure of few-electron concentric double quantum rings is
investigated within the local spin density approximation. Signatures of
inter-ring coupling in the addition energy spectrum are identified and
discussed. We show that the electronic configurations in these structures can
be greatly modulated by the inter-ring distance: At short and long distances
the low-lying electron states localize in the inner and outer rings,
respectively, and the energy structure is essentially that of an isolated
single quantum ring. However, at intermediate distances the electron states
localized in the inner and the outer ring become quasi-degenerate and a rather
entangled, strongly-correlated system is formed.Comment: 16 pages (preprint format), 6 figure
Magnetic field dependence of hole levels in self-assembled InAs quantum dots
Recent magneto-transport experiments of holes in InGaAs quantum dots [D.
Reuter, P. Kailuweit, A.D. Wieck, U. Zeitler, O. Wibbelhoff, C. Meier, A.
Lorke, and J.C. Maan, Phys. Rev. Lett. 94, 026808 (2005)] are interpreted by
employing a multi-band kp Hamiltonian, which considers the interaction between
heavy hole and light hole subbands explicitely. No need of invoking an
incomplete energy shell filling is required within this model. The crucial role
we ascribe to the heavy hole-light hole interaction is further supported by
one-band local-spin-density functional calculations, which show that Coulomb
interactions do not induce any incomplete hole shell filling and therefore
cannot account for the experimental magnetic field dispersion.Comment: 5 pages with 3 figures and one table. The paper has been submitted to
Phys.Rev.
La meteorología en la enseñanza de las ciencias experimentales : una propuesta interdisciplinar e integradora
In this paper the authors describe a possible introduction of Meteorology into the new secondary education. A didactic approach, as well as examples of contents and activities, is proposed
Generalized method of image dyons for quasi-two dimensional slabs with ordinary-topological insulator interfaces
Electrostatic charges near the interface bewteen topological (TI) and
ordinary (OI) insulators induce magnetic fields in the medium that can be
described through the so-called method of image dyons (electric charge -
magnetic monopole pairs), the magnetoelectric extension of the method of image
charges in classical electrostatics. Here, we provide the expressions for the
image dyons and ensuing magnetoelectric potentials in a system comprised by two
planar-parallel OI-TI interfaces conforming a finite-width slab. The obtained
formulae extend earlier work in that they account for all different
combinations of materials forming the slab and its surroundings, including
asymmetric systems, as well as all possible combinations of external
magnetization orientations on the interfaces. The equations are susceptible of
implementation in simple computational codes, to be solved recurrently, in
order to model magnetoelectric fields in topological quantum wells, thin films,
or layers of two-dimensional materials. We exemplify this by calculating the
magnetic fields induced by a point charge in nanometer-thick quantum wells, by
means of a Mathematica code made available in repositories.Comment: 9 pages, 7 figure
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