Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 11: Poster Session: Matter at Low Temperature

TT 11.22: Poster

Monday, March 14, 2011, 14:00–18:00, P4

Magnetorotons versus transverse magnetophonons of quasi twodimensional electrons in high magnetic fields — •Guenther Meissner and Uwe Schmitt — Theoretische Physik, Universitaet des Saarlandes, Postfach 151150, D-60041 Saarbruecken

The nature of two condensed phases: an incompressible quantum liquid of Bose-condensed charge-vortex composites and a 2D quantum solid with a lattice-periodic structure of the guiding centers of the Coulomb-interacting electrons, is investigated. Applying sum-rule techniques in a unified many-body approach, a finite gap (magnetorotons) due to correlations in the density fluctuations of the cyclotron orbits or no gap (magentophonons), because of broken magnetic translational invariance, are shown to exist rigorously in the long-wavelength limit of the low-lying collective modes. Effects of random disorder on the dispersion of the collective excitations of the two phases are investigated for a comparison with experimental results of systems exhibiting the fractional quantum Hall effect.