Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 25: Correlated Electrons: Quantum-Critical Phenomena 1

TT 25.1: Vortrag

Mittwoch, 28. März 2012, 09:30–09:45, H 3010

Deconfined quantum criticality and logarithmic violations of scaling — •Flavio Nogueira¹ and Asle Sudbo² — ¹Institut für Theoretische Physik III, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany — ²Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway

Recently logarithmic corrections to scaling were observed numerically in the so called J−Q model. These violations of standard scaling were seen in numerical measurements of the spin-stiffness at zero temperature and uniform susceptibility at finite temperature. This result led to speculations that the deconfined quantum criticality scenario has to be revised in order to explain this new feature. We use the CP^N−1 representation to derive the leading contribution to the spin stiffness at large N near the quantum critical point and show that it exhibits a logarithmic correction to scaling. This result shows that such logarithmic violations of scaling are in fact predicted by deconfined quantum criticality. Furthermore, the U(1) gauge symmetry plays a crucial role here, since models without such local gauge symmetry do not exhibit logarithmic violations of scaling in 2+1 dimensions.