Regensburg 2007 – scientific programme
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MA: Fachverband Magnetismus
MA 13: Spinstructures and magnetic Phase Transitions
MA 13.6: Talk
Tuesday, March 27, 2007, 11:30–11:45, H5
Deconfined spinons and first-order transition in easy-plane quantum antiferromagnets — •Flavio Nogueira1, Steiner Kragset2, and Asle Sudbo3 — 1Institut für Theoretische Physik, Freie Universität Berlin — 2Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway — 3Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
We report recent Monte Carlo and renormalization group results for quantum antiferromagnets in the deep easy-plane limit [1]. By performing large scale Monte Carlo simulations, we are able to show that the spinons are deconfined at the phase transition point. This is in agreement with the recently proposed scenario in which a destructive interference mechanism between instantons and the Berry phase deconfine the spinons at the phase transition. However, we show that the phase transition is first-order, in contrast with the second-order phase transition predicted by the deconfined quantum criticality scenario. Our numerical results are confirmed by a renormalization group analysis of the system at the critical point.
[1] S. Kragset, E. Smørgrav, J. Hove, F. S. Nogueira, and A. Sudbø, Phys. Rev. Lett. 97, 247201 (2006)