UCL Promotor : Benoît Hackens, Vincent Bayot
UCL Collaborators : Damien Cabosart, Thanh Nhan Bui, Frederico Rodrigues Martins, Sebastien Faniel, Sorin Melinte (ICTEAM)
External collaborations : Mansour Shayegan (Princeton U.), Jean Heremans (Virginia Tech.), Xavier Wallart (IEMN, Villeneuve d'Ascq)
Funding : FNRS
By means of advanced nanofabrication techniques, it is now possible to "squeeze" the electronic wave function in one, two or the three spatial dimensions in solid states devices. This induces quantum phenomena such as the discretization of electronic band structure. In additon, the electronic phase and momentum can be preserved over long distances compared to the system dimensions, especially at low temperatures. This gives rise to peculiar ‘mesoscopic’ transport properties, bearing signatures of electron interferences, charge discreteness, ballistic electron trajectories, electron-electron interactions, regular-chaotic electron dynamics and (in some cases) spin-orbit coupling. Examples of signatures of such effects are the weak localization effect, or Universal Conductance Fluctuations observed in the low-temperature magnetoconductance of many confined electronic systems. Electronic devices with new functionalities can be imagined based on these mesoscopic phenomena, which sometimes outperform devices based on ‘conventional’ diffusive transport.
We study this mesoscopic transport regime in nanodevices made from high mobility semiconductor heterostructures as well as graphene and thin bismuth films. Our experimental setup includes two low temperature systems (a pumped 3He system and a dilution refrigerator).
References :
- S. Faniel, B. Hackens, A. Vlad, L. Moldovan, C. Gustin, B. Habib, S. Melinte, M. Shayegan and V. Bayot, Dephasing time of two-dimensional holes in GaAs open quantum dots: Magnetotransport measurements, Physical Review B75, 193310 (2007).
- S. Faniel, E. Tutuc, E.P. De Poortere, C. Gustin, A. Vlad, S. Melinte, M. Shayegan, and V. Bayot, Thermopower of interacting GaAs bilayer hole systems in the reentrant insulating phase near nu=1, Physical Review Letters 94, 046802 (2005).
- B. hackens, S. Faniel, C. Gustin, X. Wallart, S. Bollaert, A. Cappy and V. Bayot, Dwell time limited coherence in open quantum dots, Physical Review Letters 94, 146802 (2005).
- B. Hackens, L. Gence, C. Gustin, X. Wallart, S. Bollaert, A. Cappy and V. Bayot, Sign reversal and tunable retification in a ballistic nanojunction, Applied Physics Letters 85, 4508 (2004).
- B. Hackens, J.P. Minet, S. Faniel, G. Farhi, C. Gustin, J.P. Issi, J.P. Heremans and V. Bayot, Quantum transport, anomalous dephasing and spin-orbit coupling in an open ballistic bismuth nanocavity, Physical Review B67, 121403 (2003).