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Mardi 31 mars 2009 — 14:00

Unconventional phase transitions and classical dimer models

Daniel Charrier (LPT, Toulouse)

par Pierre Pujol - 31 mars 2009

A few years ago, an interesting question has been raised about the possibility of continuous transitions between phases with different broken symmetries in quantum magnetism. While the existence of such transitions is still highly controversial in quantum spin systems, examples can be found in classical dimer models. During this seminar, I will introduce the physics of classical dimers and present an exotic phase transition in a 3d dimer model. The dimer model on a cubic lattice displays a continuous transition between an ordered columnar phase at low temperature and a disordered phase at high temperature where the correlations between dimers show an algebraic decay. We will show that the transition can be understood in terms of a Higgs mechanism, corresponding to the breaking of a "hidden" gauge symmetry. To fully characterize the order of the transition,we will also present a powerful numerical tool : the flowgram analysis.