Deconfined quantum criticality and conformal phase transition in two-dimensional antiferromagnets
1 Institut für Theoretische Physik III, Ruhr-Universität Bochum - Universitätsstraße 150, D-44801 Bochum, Germany
2 Department of Physics, Norwegian University of Science and Technology - N-7491 Trondheim, Norway
Received: 28 August 2013
Accepted: 3 December 2013
Deconfined quantum criticality of two-dimensional SU(2) quantum antiferromagnets featuring a transition from an antiferromagnetically ordered ground state to a so-called valence-bond solid state, is governed by a non-compact CP1 model with a Maxwell term in spacetime dimensions. We introduce a new perspective on deconfined quantum criticality within a field-theoretic framework based on an expansion in powers of for fixed number N of complex matter fields. We show that in the allegedly weak first-order transition regime, a so-called conformal phase transition leads to a genuine deconfined quantum critical point. In such a transition, the gap vanishes when the critical point is approached from above and diverges when it is approached from below. We also find that the spin stiffness has a universal jump at the critical point.
PACS: 64.70.Tg – Quantum phase transitions / 11.10.Kk – Field theories in dimensions other than four / 75.10.Kt – Quantum spin liquids, valence bond phases and related phenomena
© EPLA, 2013