Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Invited Talk: Clemens Rössler

HL 31.1: Invited Talk

Tuesday, March 27, 2012, 09:30–10:00, EW 203

Quantum structures on ultra clean electron gases — •Clemens Rössler, Stephan Baer, Thomas Ihn, Klaus Ensslin, Christian Reichl, and Werner Wegscheider — Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland

Since the first observation of the quantum Hall effect, the quality and the mobility of two-dimensional electron gases (2DEGs) have undergone tremendous improvements. 2DEGs defined in Al_x Ga_1−x As heterostructures can reach mobilities exceeding µ = 10⁷ cm²/Vs at low temperatures, facilitating the observation of fascinating phenomena like the microwave-induced zero-resistance states, the ν = 5/2 quantum Hall state, and interactions between composite fermions.

We investigate the transport properties of nano structures fabricated in high-mobility 2DEGs. Quantum point contacts (QPCs) profit from a strongly suppressed disorder potential, giving rise to the appearance of transport features that are obscured in standard 2DEGs. Within these conceptually simple structures, we find already a rich variety of effects like the 0.7-feature, enhanced g-factors and Aharonov-Bohm interference between edge channels forming near the QPCs. By combining two QPCs, we define quantum dots and Fabry-Perot interferometers which are investigated in the (fractional) quantum Hall regime.