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45 results on '"SORBA L."'

26. Exciton spectroscopy inZn1−xCdxSe/ZnSe quantum wells

Author

Cingolani, R., primary, Prete, P., additional, Greco, D., additional, Giugno, P. V., additional, Lomascolo, M., additional, Rinaldi, R., additional, Calcagnile, L., additional, Vanzetti, L., additional, Sorba, L., additional, and Franciosi, A., additional

Published
1995
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33. Phonons in Si/GaAs superlattices

Author

Scamarcio, G., primary, Spagnolo, V., additional, Molinari, E., additional, Tapfer, L., additional, Sorba, L., additional, Bratina, G., additional, and Franciosi, A., additional

Published
1992
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44. Probing the local temperature of a two-dimensional electron gas microdomain with a quantum dot: Measurement of electron-phonon interaction

Author

Lucia Sorba, Francesco Giazotto, Giorgio Biasiol, F. Deon, Fabio Beltram, Simone Gasparinetti, Gasparinetti, S, Deon, F, Biasiol, G, Sorba, L, Beltram, Fabio, and Giazotto, F.

Subjects
Thermal equilibrium, Materials science, Condensed matter physics, Phonon, Nanowire, Coulomb blockade, 02 engineering and technology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Quantum dot, 0103 physical sciences, Quasiparticle, Electron temperature, 010306 general physics, 0210 nano-technology, Quantum tunnelling
Abstract

The analysis of the performance and the very understanding of the physical mechanisms governing the behavior of nanostructured devices requires the detailed knowledge of all parameters of electronic systems confined in ever shrinking microdomains. The role of temperature and the investigation of heat transport in solidstate nanoscale systems are currently under the spotlight [1]. Electronic thermometers [2‐4], refrigerators [5‐8] and heat transistors [9] based on metallic and superconductor nanostructures were already demonstrated. Such devices are typically operated at subkelvin temperatures, where electron-phonon interaction is weak and, as a result, the relevant electronic temperature may significantly dier from that of the lattice (if at all defined). In this context, the ability to perform local measurements of the electronic temperature becomes highly desirable. While in metallic systems superconducting tunnel junctions are routinely employed for this purpose, for the case of two-dimensional electron gases (2DEGs) or semiconductor nanowires at thermal equilibrium, quantum dots (QDs) were shown to be suitable for absolute thermometry [10, 11], due to the fact that in these conditions the linewidth of zero-bias Coulomb blockade (CB) peaks in the weak-coupling regime is directly related to the electronic temperature of the leads. Here, we propose a method for the detection of the local electronic temperature in a 2DEG, based on the analysis of the CB-peak lineshape. We shall first discuss zero-bias transport through a weakly-coupled QD in the presence of a temperature bias and show that zerobias conductance measurements can be used to experimentally determine both temperature values. We shall then employ this technique to investigate energy relaxation mechanisms in an electronic microdomain defined electrostatically in a GaAs/AlGaAs heterostructure and heated by an externally-driven current. The domain is connected to the surrounding 2DEG regions through the QD and three quantum point contacts (QPCs). As a known heating power is delivered to the domain, conductance across the QD is probed and the steady-state temperature detected. The dependence of the measured electron temperature on heating power will also be studied for dierent values of the QPC resistances: as the coupling to the surrounding 2DEG regions is reduced, we observe the crossover from a regime where excess heat is carried away by hot quasiparticles tunneling through the QPCs to one where power exchange with lattice phonons dominates. We shall show that the latter mechanism follows the T 5 power law expected [12] for the screened electron-acoustic phonon piezoelectric interaction, and obtain a measurement of the relative coupling constant consistent with theoretical estimates [1, 13].

Published
2011
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45. Spatially resolved analysis of edge-channel equilibration in quantum Hall circuits

Author

Fabio Taddei, Lucia Sorba, Stefan Heun, Rosario Fazio, Giorgio Biasiol, Stefano Roddaro, Vittorio Giovannetti, Nicola Paradiso, Davide Venturelli, Fabio Beltram, Paradiso, N, Heun, S, Roddaro, S, Venturelli, Davide, Taddei, F, Giovannetti, Vittorio, Fazio, Rosario, Biasiol, G, Sorba, L, and Beltram, Fabio

Subjects
Physics, Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, FOS: Physical sciences, Charge (physics), Quantum Hall effect, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Computational physics, Quantum spin Hall effect, Quantum mechanics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Astronomical interferometer, Quantum Physics (quant-ph), Quantum, Realization (systems), Beam (structure), Electronic circuit
Abstract

Istituto Officina dei Materiali CNR, Laboratorio TASC, Basovizza (TS), Italy(Dated: February 22, 2011)We demonstrate an innovative quantum Hall circuit with variable geometry employing the move-able electrostatic potential induced by a biased atomic force microscope tip. We exploit this ad-ditional degree of freedom to identify the microscopic mechanisms that allow two co–propagatingedge channels to equilibrate their charge imbalance. Experimental results are compared with tight–binding simulations based on a realistic model for the disorder potential. This work provides alsoan experimental realization of a beam mixer between co–propagating edge channels, a still elusivebuilding block of a recently proposed new class of quantum interferometers.

Published
2011
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