1,798 research outputs found
Coulomb blockade at a tunnel junction between two quantum wires with long-range interaction
The non-linear current-voltage characteristic of a tunnel junction between
two Luttinger systems is calculated for an interaction with finite range.
Coulomb blockade features are found. The dissipative resistance, the
capacitance and the external impedance, which were introduced ad hoc in earlier
theories, are obtained in terms of the electron-electron interaction. The
frequency dependence of the impedance is given by the excitation spectrum of
the electrons.Comment: 5 pages, RevTeX, 2 figures, to be published in Solid State
Communication
Magnetic AC control of the spin textures in a helical Luttinger liquid
We demonstrate the possibility to induce and control peculiar spin textures
in a helical Luttinger liquid, by means of a time-dependent magnetic scatterer.
The presence of a perturbation that breaks the time-reversal symmetry opens a
gap in the spectrum, inducing single-particle backscattering and a peculiar
spin response. We show that in the weak backscattering regime asymmetric spin
textures emerge at the left and right side of the scatterer, whose spatial
oscillations are controlled by the ratio between the magnetization frequency
and the Fermi energy and by the electron interaction. This peculiar spin
response marks a strong difference between helical and non-helical liquids,
which are expected to produce symmetric spin textures even in the AC regime.Comment: 7 pages, 4 figure
Non-linear Coulomb blockade microscopy of a correlated one-dimensional quantum dot
We evaluate the chemical potential of a one-dimensional quantum dot, coupled
to an atomic force microscope tip. The dot is described within the Luttinger
liquid framework and the conductance peaks positions as a function of the tip
location are calculated in the linear and non-linear transport regimes for an
arbitrary number of particles. The differences between the chemical potential
oscillations induced by Friedel and Wigner terms are carefully analyzed in the
whole range of interaction strength. It is shown that Friedel oscillations,
differently from the Wigner ones, are sensitive probes to detect excited spin
states and collective spin density waves involved in the transport.Comment: 4 figure
Temperature-induced emergence of Wigner correlations in a STM-probed one-dimensional quantum dot
The temperature-induced emergence of Wigner correlations over finite-size
effects in a strongly interacting one-dimensional quantum dot are studied in
the framework of the spin coherent Luttinger liquid. We demonstrate that, for
temperatures comparable with the zero mode spin excitations, Friedel
oscillations are suppressed by the thermal fluctuations of higher spin modes.
On the other hand, the Wigner oscillations, sensitive to the charge mode only,
are stable and become more visible. This behavior is proved to be robust both
in the thermal electron density and in the linear conductance in the presence
of an STM tip. This latter probe is not directly proportional to the electron
density and may confirm the above phenomena with complementary and additional
information
AFM probe for the signatures of Wigner correlations in the conductance of a one-dimensional quantum dot
The transport properties of an interacting one-dimensional quantum dot
capacitively coupled to an atomic force microscope probe are investigated. The
dot is described within a Luttinger liquid framework which captures both
Friedel and Wigner oscillations. In the linear regime, we demonstrate that both
the conductance peak position and height oscillate as the tip is scanned along
the dot. A pronounced beating pattern in the conductance maximum is observed,
connected to the oscillations of the electron density. Signatures of the
effects induced by a Wigner molecule are clearly identified and their stability
against the strength of Coulomb interactions are analyzed. While the
oscillations of the peak position due to Wigner get enhanced at strong
interactions, the peak height modulations are suppressed as interactions grow.
Oscillations due to Friedel, on the other hand, are robust against interaction.Comment: 9 figure
Theory of the STM detection of Wigner molecules in spin incoherent CNTs
The linear conductance of a carbon nanotube quantum dot in the Wigner
molecule regime, coupled to two scanning tunnel microscope tips is inspected.
Considering the high temperature regime, the nanotube quantum dot is described
by means of the spin-incoherent Luttinger liquid picture. The linear
conductance exhibits spatial oscillations induced by the presence of the
correlated, molecular electron state. A power-law scaling of the electron
density and of the conductance as a function of the interaction parameter are
found. They confirm local transport as a sensitive tool to investigate the
Wigner molecule. The double-tip setup allows to explore different transport
regimes with different shapes of the spatial modulation, all bringing
information about the Wigner molecule
Probing Wigner correlations in a suspended carbon nanotube
The influence of the electron-vibron coupling on the transport properties of
a strongly interacting quantum dot built in a suspended carbon nanotube is
analyzed. The latter is probed by a charged AFM tip scanned along the axis of
the CNT which induces oscillations of the chemical potential and of the linear
conductance. These oscillations are due to the competition between finite-size
effects and the formation of a Wigner molecule for strong interactions. Such
oscillations are shown to be suppressed by the electron-vibron coupling. The
suppression is more pronounced in the regime of weak Coulomb interactions,
which ensures that probing Wigner correlations in such a system is in principle
possible
Local fields in nonlinear quantum transport
We investigate the dynamical interplay between currents and electromagnetic
fields in frequency-dependent transport through a single-channel quantum wire
with an impurity potential in the presence of electron-electron interactions.
We introduce and discuss a formalism which allows a self-consistent treatment
of currents and electromagnetic fields.Comment: 4 page
Generating and controlling spin-polarized currents induced by a quantum spin Hall antidot
We study an electrically controlled quantum spin Hall antidot embedded in a
two-dimensional topological insulating bar. Helical edge states around the
antidot and along the edges of the bar are tunnel coupled. The close connection
between spin and chirality, typical of helical systems, allows to generate a
spin-polarized current flowing across the bar. This current is studied as a
function of the external voltages, by varying the asymmetry between the
barriers. For asymmetric setups, a switching behavior of the spin current is
observed as the bias is increased, both in the absence and in the presence of
electron interactions. This device allows to generate and control the
spin-polarized current by simple electrical means.Comment: 7 pages, 6 figure
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