BGU Physics Department

Colloquium, Nov. 28th, 2013

Scanning Gate Microscopy and Quantum Point Contacts

Jean-Louis Pichard, CEA Saclay, France

The conductance of the electron interferometer formed in a two dimensional electron gas between a quantum contact and the depletion region induced by the charged tip of a scanning gate microscope exhibits very unusual interference behaviors. This can be seen when one studies the interferometer conductance as a function of the position of the tip, of the opening of the contact and of the temperature.
Using a solvable model where the contact exhibits a simple spin-degenerate Breit-Wigner resonance, I shall explain the enhancement of the interference fringes induced by increasing the temperature [1] and the interference rings occurring in addition to fringes space by half the Fermi wavelength when the resonance is split by a Zeeman Field [2].
The observation of these two phenomena using either a quantum point contact or a Kondo dot above its Kondo temperature for the contact region will be eventually discussed.
[1] “Thermal Enhancement of Interference Effects in Quantum point Contacts”, Adel Abbout, Gabriel Lemarié and Jean-Louis Pichard, Phys. Rev. Lett. 106, 156810 (2011).
[2] “Scanning Gate Microscopy of Kondo Dots: Fabry-Pérot Interferences and Thermally Induced Rings”, Andrii Kleshchonok, Geneviève Fleury and Jean-Louis Pichard, arXiv:1305.0106 (2013).