172 research outputs found
Probing the local temperature of a 2DEG microdomain with a quantum dot: measurement of electron-phonon interaction
We demonstrate local detection of the electron temperature in a
two-dimensionalmicrodomain using a quantum dot. Our method relies on the
observation that a temperature bias across the dot changes the functional form
of Coulomb-blockade peaks. We apply our results to the investigation of
electron-energy relaxation at subkelvin temperatures, find that the energy flux
from electrons into phonons is proportional to the fifth power of temperature,
and give a measurement of the coupling constant.Comment: 5 pages, 4 figure
Hybrid InAs nanowire-vanadium proximity SQUID
We report the fabrication and characterization of superconducting quantum
interference devices (SQUIDs) based on InAs nanowires and vanadium
superconducting electrodes. These mesoscopic devices are found to be extremely
robust against thermal cycling and to operate up to temperatures of ~K
with reduced power dissipation. We show that our geometry allows to obtain
nearly-symmetric devices with very large magnetic-field modulation of the
critical current. All these properties make these devices attractive for
on-chip quantum-circuit implementation.Comment: 3 pages, 3 figure
Inter-edge strong-to-weak scattering evolution at a constriction in the fractional quantum Hall regime
Gate-voltage control of inter-edge tunneling at a split-gate constriction in
the fractional quantum Hall regime is reported. Quantitative agreement with the
behavior predicted for out-of-equilibrium quasiparticle transport between
chiral Luttinger liquids is shown at low temperatures at specific values of the
backscattering strength. When the latter is lowered by changing the gate
voltage the zero-bias peak of the tunneling conductance evolves into a minimum
and a non-linear quasihole-like characteristic emerges. Our analysis emphasizes
the role of the local filling factor in the split-gate constriction region.Comment: 4 pages, 4 figure
Tuning non-linear charge transport between integer and fractional quantum Hall states
Controllable point junctions between different quantum Hall phases are a
necessary building block for the development of mesoscopic circuits based on
fractionally-charged quasiparticles. We demonstrate how particle-hole duality
can be exploited to realize such point-contact junctions. We show an
implementation for the case filling factors and in which
both the fractional filling and the coupling strength can be finely and
independently tuned. A peculiar crossover from insulating to conducting
behavior as goes from 1/3 to 1 is observed. These results highlight the
key role played on inter-edge tunneling by local charge depletion at the point
contact.Comment: 4 pages, 3 figures, suppl.ma
Mapping of Axial Strain in InAs/InSb Heterostructured Nanowires
The article presents a mapping of the residual strain along the axis of
InAs/InSb heterostructured nanowires. Using confocal Raman measurements, we
observe a gradual shift in the TO phonon mode along the axis of these
nanowires. We attribute the observed TO phonon shift to a residual strain
arising from the InAs/InSb lattice mismatch. We find that the strain is maximum
at the interface and then monotonically relaxes towards the tip of the
nanowires. We also analyze the crystal structure of the InSb segment through
selected area electron diffraction measurements and electron diffraction
tomography on individual nanowires.Comment: 14 pages, 5 figure
Surface Nano-Patterning for the Bottom-Up Growth of III-V Semiconductor Nanowire Ordered Arrays
Ordered arrays of vertically aligned semiconductor nanowires are regarded as promising candidates for the realization of all-dielectric metamaterials, artificial electromagnetic materials, whose properties can be engineered to enable new functions and enhanced device performances with respect to naturally existing materials. In this review we account for the recent progresses in substrate nanopatterning methods, strategies and approaches that overall constitute the preliminary step towards the bottom-up growth of arrays of vertically aligned semiconductor nanowires with a controlled location, size and morphology of each nanowire. While we focus specifically on III-V semiconductor nanowires, several concepts, mechanisms and conclusions reported in the manuscript can be invoked and are valid also for different nanowire materials
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