Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 22: Correlated Electrons: Quantum-Critical Phenomena 2
TT 22.12: Vortrag
Mittwoch, 25. März 2009, 12:45–13:00, HSZ 03
Quantum phase transitions in systems of coupled spin dimers — •Sandro Wenzel1, Wolfhard Janke1, and Stefan Wessel2 — 1Institut für Theoretische Physik, Universität Leipzig, Postfach 100 920, 04109 Leipzig — 2Institut für Theoretische Physik III, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart
We study quantum phase transitions in two-dimensional periodic arrangements of coupled spin-1/2 dimers, using a combination of quantum Monte Carlo simulations and effective field theories. Our numerical results on both ground-state properties and the finite-temperature scaling behavior in the quantum critical regime indicate, that depending on the spatial arrangement of the dimers, deviations occur to the scaling behavior of the three-dimensional Heisenberg universality class. We discuss the numerical evidence [1] for such unconventional quantum criticality, and possible relations to low-energy continuum theory beyond the conventional non-linear sigma model action.
[1] S. Wenzel, L. Bogacz, W. Janke, Phys. Rev. Lett. 101, 127202 (2008).