Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 9: Poster I
HL 9.79: Poster
Montag, 27. März 2006, 15:15–17:45, P3
Magnetotransportmeasurements and electron counting on GaAs/AlGaAs quantum rings — •A. Mühle1, R. J. Haug1, W. Wegscheider2, and M. Bichler3 — 1Institut für Festkörperphysik, Universität Hannover, D-30167 Hannover — 2Angewandte und Experimentelle Physik, Universität Regensburg, D-92040 Regensburg — 3Walter Schottky Institut, TU München, D-85748 Garching
We present transport measurements done in dependence of an external magnetic field on quantum rings on the surface of GaAs/AlGaAs heterostructures. These rings were fabricated by atomic force microscope lithography utilising local anodic oxidation [1]. Using in-plane gates, the energy of the electrons in the arms of the rings as well as the coupling of the structures to the leads can be controlled.
While sweeping the magnetic field in the regime with only few electrons on the ring, it is possible to determine their exact number if certain features in the transport spectrum can be observed namely Kondo effect and spin-flips.
Additionally, a setup with a quantum point contact next to a quantum ring can be used to count the electrons on the ring by utilizing the influence of the ring’s charge on the conductance of the point contact.
[1] U. F. Keyser et al., Phys. Rev. Lett. 90, 196601-1 (2003)