TOPOLOGICAL-SECTOR FLUCTUATIONS AT THE BEREZINSKII-KOSTERLITZ-THOULESS TRANSITION
Mardi 10 novembre 2015 11:30
- Duree : 1 heure
Lieu : ILL 4, Seminar Room (no 158), 71 avenue des Martyrs - Grenoble
Orateur : Michael FAULKNER (University College London & ENS Lyon)
The Berezinskii-Kosterlitz-Thouless (BKT) phase transition [1,2] drives the unbinding of local topological defects in many two-dimensional systems. One such system is the two-dimensional Coulomb gas, where it corresponds to an insulator-conductor transition [3] driven by charge deconfinement. We investigate the global topological properties of this transition using a Maggs-Rossetto (MR) lattice-field description [4] of the two-dimensional Coulomb gas on a torus. The BKT transition is shown to be an ergodicity breaking between the topological sectors of the electric field, which implies a definition of the topological order of the system [2] in terms of broken ergodicity. We use the MR electric-field representation of 2D-XY models to show that these signatures could be detected in experiments on, for example, magnetic films and cold-atom systems.
[1] Berezinskii, Sov. Phys.-JETP 32 493 (1971)
[2] Kosterlitz and Thouless, J. Phys. C : Solid State Phys. 6 1181 (1973)
[3] Salzberg and Prager, J. Chem. Phys. 38 2587 (1963)
[4] Maggs and Rossetto, Phys. Rev. Lett. 88 196402 (2002)
Contact : taffut@ill.fr
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