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Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 32: MLT: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 2

TT 32.4: Hauptvortrag

Donnerstag, 25. März 2010, 14:45–15:15, H18

Dispersion of the Excitations of Fractional Quantum Hall States — •Jurgen Smet1, Igor Kukushkin1,2, Vito Scarola3,4, Vladimir Umansky5, and Klaus von Klitzing11Max-Planck-Institute for Solid State Research, Stuttgart, Germany — 2Institute of Solid State Physics, Russian Academy of Science, Chernogolovka, Russia — 3Department of Chemistry and Pitzer Center for Theoretical Chemistry, University of California at Berkeley, USA — 4Theoretische Physik, ETH Zürich, Switzerland — 5Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel

The rich correlation physics in two-dimensional (2D) electron systems is governed by the dispersion of its excitations. In the fractional quantum Hall regime, excitations involve fractionally charged quasi particles, which exhibit dispersion minima at large momenta referred to as rotons. These rotons are difficult to access with conventional techniques because of the lack of penetration depth or sample volume. Our method overcomes the limitations of conventional methods and traces the dispersion of excitations across momentum space for buried systems involving small material volume. We used surface acoustic waves, launched across the 2D system, to allow incident radiation to trigger these excitations at large momenta. Optics probed their resonant absorption. Our technique unveils the full dispersion of such excitations of several prominent correlated ground states of the 2D electron system, which has so far been inaccessible for experimentation.

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