80 research outputs found
Effects of Electron-Electron Scattering on Electron-Beam Propagation in a Two-Dimensional Electron-Gas
We have studied experimentally and theoretically the influence of
electron-electron collisions on the propagation of electron beams in a
two-dimensional electron gas for excess injection energies ranging from zero up
to the Fermi energy. We find that the detector signal consists of
quasiballistic electrons, which either have not undergone any electron-electron
collisions or have only been scattered at small angles. Theoretically, the
small-angle scattering exhibits distinct features that can be traced back to
the reduced dimensionality of the electron system. A number of nonlinear
effects, also related to the two-dimensional character of the system, are
discussed. In the simplest situation, the heating of the electron gas by the
high-energy part of the beam leads to a weakening of the signal of
quasiballistic electrons and to the appearance of thermovoltage. This results
in a nonmonotonic dependence of the detector signal on the intensity of the
injected beam, as observed experimentally.Comment: 9 pages, 7 figure
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Ultrafast nonlocal collective dynamics of Kane plasmon-polaritons in a narrow-gap semiconductor
The observation of ultrarelativistic fermions in condensed-matter systems has uncovered a cornucopia of novel phenomenology as well as a potential for effective ultrafast light engineering of new states of matter. While the nonequilibrium properties of two- and three-dimensional (2D and 3D) hexagonal crystals have been studied extensively, our understanding of the photoinduced dynamics in 3D single-valley ultrarelativistic materials is, unexpectedly, lacking. Here, we use ultrafast scanning near-field optical spectroscopy to access and control nonequilibrium large-momentum plasmon-polaritons in thin films of a prototypical narrow-bandgap semiconductor Hg0.81Cd0.19Te. We demonstrate that these collective excitations exhibit distinctly nonclassical scaling with electron density characteristic of the ultrarelativistic Kane regime and experience ultrafast initial relaxation followed by a long-lived highly coherent state. Our observation and ultrafast control of Kane plasmon-polaritons in a semiconducting material using light sources in the standard telecommunications fiber-optics window open a new avenue toward high-bandwidth coherent information processing in next-generation plasmonic circuits
Quantum effects in thermal and thermo-electric transport in semiconductor nanostructures
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Thermal and thermo-electric transport properties of quantum point contacts
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Thermo-electric properties of quantum point contacts
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Magnetoconductance of two point contacts in series
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Voltage-probe-controlled breakdown of the quantum Hall effect
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Selective backscattering and the breakdown of the quantum Hall effect
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Quantum oscillations in the transverse voltage of a channel in the non-linear transport regime
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
Sawtooth-like thermopower oscillations of a quantum dot in the Coulomb blockade regime
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
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