Europhys. Lett.
Volume 74, Number 5, June 2006
Page(s) 896 - 902
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 05 May 2006
Europhys. Lett., 74 (5), pp. 896-902 (2006)
DOI: 10.1209/epl/i2006-10039-3

Frustrated Heisenberg antiferromagnets: Fluctuation-induced first order vs. deconfined quantum criticality

F. Krüger1 and S. Scheidl2

1  Instituut-Lorentz, Universiteit Leiden - P.O. Box 9506 2300 RA Leiden, The Netherlands
2  Institut für Theoretische Physik, Universität zu Köln Zülpicher Str. 77, D-50937 Köln, Germany

received 11 January 2006; accepted in final form 7 April 2006
published online 5 May 2006

Recently it was argued that quantum phase transitions can be radically different from classical phase transitions with, as a highlight, the "deconfined critical points" exhibiting fractionalization of quantum numbers due to Berry phase effects. Such transitions are supposed to occur in frustrated ("J1-J2") quantum magnets. We have developed a novel renormalization approach for such systems which is fully respecting the underlying lattice structure. According to our findings, another profound phenomenon is around the corner: a fluctuation-induced (order-out-of-disorder) first-order transition. This has to occur for large spin and we conjecture that it is responsible for the weakly first-order behavior recently observed in numerical simulations for frustrated S=1/2 systems.

75.30.Kz - Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.).
75.50.Ee - Antiferromagnetics.
05.10.Cc - Renormalization group methods.

© EDP Sciences 2006