5,225 research outputs found
Tunable circular dipolelike system in graphene: Mixed electron-hole states
Coupled electron-hole states are realized in a system consisting of a
combination of an electrostatic potential barrier and ring-shaped potential
well, which resembles a circular dipole. A perpendicular magnetic field induces
confined states inside the Landau gaps which are mainly located at the barrier
or ring. Hybridizations between the barrier and ring states are seen as
anticrossings in the energy spectrum. As a consequence, the energy levels show
an oscillating dependence on the electrostatic potential strength in
combination with an oscillating migration of the wave functions between the
barrier and ring. At the anticrossing points the quantum state consists of a
mixture of electron and hole. The present system mimics closely the behavior of
a relativistic dipole on gapped graphene.Comment: 9 pages and 9 figure
Quantum Transport Characteristics of Lateral pn-Junction of Single Layer TiS3
Using density functional theory and nonequilibrium Greens functions-based
methods we investigated the electronic and transport properties of monolayer
TiS3 pn-junction. We constructed a lateral pn-junction in monolayer TiS3 by
using Li and F adatoms. An applied bias voltage caused significant variability
in the electronic and transport properties of the TiS3 pn-junction. In
addition, spin dependent current-voltage characteristics of the constructed
TiS3 pn-junction were analyzed. Important device characteristics were found
such as negative differential resistance and rectifying diode behaviors for
spin-polarized currents in the TiS3 pn-junction. These prominent conduction
properties of TiS3 pn-junction offer remarkable opportunities for the design of
nanoelectronic devices based on a recently synthesized single-layered material
Ag and Au Atoms Intercalated in Bilayer Heterostructures of Transition Metal Dichalcogenides and Graphene
The diffusive motion of metal nanoparticles Au and Ag on monolayer and
between bilayer heterostructures of transition metal dichalcogenides and
graphene are investigated in the framework of density functional theory. We
found that the minimum energy barriers for diffusion and the possibility of
cluster formation depend strongly on both the type of nanoparticle and the type
of monolayers and bilayers. Moreover, the tendency to form clusters of Ag and
Au can be tuned by creating various bilayers. Tunability of the diffusion
characteristics of adatoms in van der Waals heterostructures holds promise for
controllable growth of nanostructures.Comment: accepted, APL Ma
Dynamics of self-organized driven particles with competing range interaction
Non-equilibrium self-organized patterns formed by particles interacting
through competing range interaction are driven over a substrate by an external
force. We show that, with increasing driving force, the pre-existed static
patterns evolve into dynamic patterns either via disordered phase or depinned
patterns, or via the formation of non-equilibrium stripes. Strikingly, the
stripes are formed either in the direction of the driving force or in the
transverse direction, depending on the pinning strength. The revealed dynamical
patterns are summarized in a dynamical phase diagram.Comment: 8 pages, 11 figure
Fluxonic Cellular Automata
We formulate a new concept for computing with quantum cellular automata
composed of arrays of nanostructured superconducting devices. The logic states
are defined by the position of two trapped flux quanta (vortices) in a 2x2
blind-hole-matrix etched on a mesoscopic superconducting square. Such small
computational unit-cells are well within reach of current fabrication
technology. In an array of unit-cells, the vortex configuration of one cell
influences the penetrating flux lines in the neighboring cell through the
screening currents. Alternatively, in conjoined cells, the information transfer
can be strengthened by the interactions between the supercurrents in adjacent
cells. Here we present the functioning logic gates based on this fluxonic
cellular automata (FCA), where the logic operations are verified through
theoretical simulations performed in the framework of the time-dependent
Ginzburg-Landau theory. The input signals are defined by current loops placed
on top of the two diagonal blind holes of the input cell. For given
current-polarization, external flux lines are attracted or repelled by the
loops, forming the '0' or '1' configuration. The read-out technology may be
chosen from a large variety of modern vortex imaging methods, transport and
LDOS measurements.Comment: Featured on the cover page of APL, November 2007 issu
Violation of Onsager symmetry for a ballistic channel Coulomb coupled to a quantum ring
We investigate a scattering of electron which is injected individually into
an empty ballistic channel containing a cavity that is Coulomb coupled to a
quantum ring charged with a single-electron.
We solve the time-dependent Schr\"odinger equation for the electron pair with
an exact account for the electron-electron correlation. Absorption of energy
and angular momentum by the quantum ring is not an even function of the
external magnetic field. As a consequence we find that the electron
backscattering probability is asymmetric in the magnetic field and thus
violates Onsager symmetry.Comment: submitted to EP
Electron transfer through a multiterminal quantum ring: magnetic forces and elastic scattering effects
We study electron transport through a semiconductor quantum ring with one
input and two output terminals for an elastic scatterer present within one of
the arms of the ring. We demonstrate that the scatterer not only introduces
asymmetry in the transport probability to the two output leads but also reduces
the visibility of the Aharonov-Bohm conductance oscillations. This reduction
occurs in spite of the phase coherence of the elastic scattering and is due to
interruption of the electron circulation around the ring by the potential
defect. The results are in a qualitative agreement with a recent experiment by
Strambini et al. [Phys. Rev. B {\bf 79}, 195443 (2009)]. We also indicate that
the magnetic symmetry of the sum of conductance of both the output leads as
obtained in the experiment can be understood as resulting from the invariance
of backscattering to the input lead with respect to the magnetic field
orientation.Comment: submitted to PR
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