64 research outputs found
Getting information from the mixed electrical-heat noise
We give a classification of the different types of noise in a quantum dot,
for variable temperature, voltage and frequency. It allows us first to show
which kind of information can be extracted from the electrical noise, such as
the ac-conductance or the Fano factor. And next, to classify the mixed
electrical-heat noise, and to identify in which regimes information on the
Seebeck coefficient, on the thermoelectric figure of merit, or on the
thermoelectric efficiency can be obtained.Comment: Proceeding of the ICNF 2017 conference, IEEE, International
Conference on Noise and Fluctuations (2017
Anomalous Hall effect and weak localization corrections in a ferromagnet
In this paper, we report results on the anomalous Hall effect. First, we
summarize analytical calculations based on the Kubo formalism : explicit
expressions for both skew-scattering and side-jump are derived and
weak-localization corrections are discussed. Next, we present numerical
calculations of the anomalous Hall resistivity based on the Dirac equation.
Qualitative agreement with experiments is obtained.Comment: Proceeding JEMS'0
An electronic Mach-Zehnder interferometer in the Fractional Quantum Hall effect
We compute the interference pattern of a Mach-Zehnder interferometer
operating in the fractional quantum Hall effect. Our theoretical proposal is
inspired by a remarkable experiment on edge states in the Integer Quantum Hall
effect (IQHE). The Luttinger liquid model is solved via two independent
methods: refermionization at nu=1/2 and the Bethe Ansatz solution available for
Laughlin fractions. The current differs strongly from that of single electrons
in the strong backscattering regime. The Fano factor is periodic in the flux,
and it exhibits a sharp transition from sub-Poissonian (charge e/2) to
Poissonian (charge e) in the neighborhood of destructive interferences
Localization corrections to the anomalous Hall effect in a ferromagnet
We calculate the localization corrections to the anomalous Hall conductivity
related to the contribution of spin-orbit scattering into the current vertex
(side-jump mechanism). We show that in contrast to the ordinary Hall effect,
there exists a nonvanishing localization correction to the anomalous Hall
resistivity. The correction to the anomalous Hall conductivity vanishes in the
case of side-jump mechanism, but is nonzero for the skew scattering. The total
correction to the nondiagonal conductivity related to both mechanisms, does not
compensate the correction to the diagonal conductivity.Comment: 7 pages with 7 figure
Anomalous Hall effect in Rashba two-dimensional electron systems based on narrow-band semiconductors: side-jump and skew scattering mechanisms
We employ a helicity-basis kinetic equation approach to investigate the
anomalous Hall effect in two-dimensional narrow-band semiconductors considering
both Rashba and extrinsic spin-orbit (SO) couplings, as well as a SO coupling
directly induced by an external driving electric field. Taking account of
long-range electron-impurity scattering up to the second Born approximation, we
find that the various components of the anomalous Hall current fit into two
classes: (a) side-jump and (b) skew scattering anomalous Hall currents. The
side-jump anomalous Hall current involves contributions not only from the
extrinsic SO coupling but also from the SO coupling due to the driving electric
field. It also contains a component which arises from the Rashba SO coupling
and relates to the off-diagonal elements of the helicity-basis distribution
function. The skew scattering anomalous Hall effect arises from the anisotropy
of the diagonal elements of the distribution function and it is a result of
both the Rashba and extrinsic SO interactions. Further, we perform a numerical
calculation to study the anomalous Hall effect in a typical InSb/AlInSb quantum
well. The dependencies of the side-jump and skew scattering anomalous Hall
conductivities on magnetization and on the Rashba SO coupling constant are
examined.Comment: 16 pages, 4 figures, accepted for publication in PR
AC conductance and non-symmetrized noise at finite frequency in quantum wires and carbon nanotubes
We calculate the AC conductance and the finite-frequency non-symmetrized
noise in interacting quantum wires and single-wall carbon nanotubes in the
presence of an impurity. We observe a strong asymmetry in the frequency
spectrum of the non-symmetrized excess noise, even in the presence of the
metallic leads. We find that this asymmetry is proportional to the differential
excess AC conductance of the system, defined as the difference between the AC
differential conductances at finite and zero voltage, and thus disappears for a
linear system. In the quantum regime, for temperatures much smaller than the
frequency and the applied voltage, we find that the emission noise is exactly
equal to the impurity partition noise. For the case of a weak impurity we
expand our results for the AC conductance and the noise perturbatively. In
particular, if the impurity is located in the middle of the wire or at one of
the contacts, our calculations show that the noise exhibits oscillations with
respect to frequency, whose period is directly related to the value of the
interaction parameter
Electron injection in a nanotube with leads: finite frequency noise-correlations and anomalous charges
The non-equilibrium transport properties of a carbon nanotube which is
connected to Fermi liquid leads, where electrons are injected in the bulk, are
computed. A previous work which considered an infinite nanotube showed that the
zero frequency noise correlations, measured at opposite ends of the nanotube,
could be used to extract the anomalous charges of the chiral excitations which
propagate in the nanotube. Here, the presence of the leads have the effect that
such-noise cross-correlations vanish at zero frequency. Nevertheless,
information concerning the anomalous charges can be recovered when considering
the spectral density of noise correlations at finite frequencies, which is
computed perturbatively in the tunneling amplitude. The spectrum of the noise
cross-correlations is shown to depend crucially on the ratio of the time of
flight of quasiparticles traveling in the nanotube to the ``voltage'' time
which defines the width of the quasiparticle wave-packets injected when an
electron tunnels. Potential applications toward the measurement of such
anomalous charges in non-chiral Luttinger liquids (nanotubes or semiconductor
quantum wires) are discussed.Comment: 11 pages, 5 figure
Anomalous Hall effect in a two-dimensional electron gas with spin-orbit interaction
We discuss the mechanism of anomalous Hall effect related to the contribution
of electron states below the Fermi surface (induced by the Berry phase in
momentum space). Our main calculations are made within a model of
two-dimensional electron gas with spin-orbit interaction of the Rashba type,
taking into account the scattering from impurities. We demonstrate that such an
"intrinsic" mechanism can dominate but there is a competition with the
impurity-scattering mechanism, related to the contribution of states in the
vicinity of Fermi surface. We also show that the contribution to the Hall
conductivity from electron states close to the Fermi surface has the intrinsic
properties as well.Comment: 9 pages, 6 figure
Screening of a Luttinger liquid wire by a scanning tunneling microscope tip: I. Spectral properties
The screening effect due to a scanning tunneling microscope tip which is
placed in the vicinity of an interacting quantum wire is considered. With the
help of a bosonization procedure, we are able to determine non perturbatively
the Green's functions of the quantum wire in the presence of both electrostatic
screening by the tip and Coulomb interactions in the wire. In our approach we
justify that the working Hamiltonian of the whole system is quadratic when
and can be solved by integration over the degrees of freedom of the
tip. Once the Green's functions are known, we calculate the spectral
properties. We show that the spectral function, as well as the tunnel density
of states, is affected by the screening and that the local density of states
strongly deviates from its unscreened value when the tip gets close to the
wire. Moreover, we observe that the spatial extension of the deviation of the
local density of states is related to both the Coulomb interactions parameter
and the screening strength
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