Diagnosing weakly first-order phase transitions by coupling to order parameters
Jonathan D'Emidio, Alexander A. Eberharter, Andreas M. Läuchli
SciPost Phys. 15, 061 (2023) · published 14 August 2023
- doi: 10.21468/SciPostPhys.15.2.061
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Abstract
The hunt for exotic quantum phase transitions described by emergent fractionalized degrees of freedom coupled to gauge fields requires a precise determination of the fixed point structure from the field theoretical side, and an extreme sensitivity to weak first-order transitions from the numerical side. Addressing the latter, we revive the classic definition of the order parameter in the limit of a vanishing external field at the transition. We demonstrate that this widely understood, yet so far unused approach provides a diagnostic test for first-order versus continuous behavior that is distinctly more sensitive than current methods. We first apply it to the family of $Q$-state Potts models, where the nature of the transition is continuous for $Q\leq4$ and turns (weakly) first order for $Q>4$, using an infinite system matrix product state implementation. We then employ this new approach to address the unsettled question of deconfined quantum criticality in the $S=1/2$ Néel to valence bond solid transition in two dimensions, focusing on the square lattice $J$-$Q$ model. Our quantum Monte Carlo simulations reveal that both order parameters remain finite at the transition, directly confirming a first-order scenario with wide reaching implications in condensed matter and quantum field theory.
Cited by 10
Authors / Affiliations: mappings to Contributors and Organizations
See all Organizations.- 1 Donostia International Physics Center [DIPC]
- 2 Institut für Theoretische Physik / Institute for Theoretical Physics, University of Innsbruck [ITP]
- 3 Paul Scherrer Institute [PSI]
- 4 École Polytechnique Fédérale de Lausanne [EPFL]
- Austrian Science Fund (FWF) (through Organization: Fonds zur Förderung der wissenschaftlichen Forschung / FWF Austrian Science Fund [FWF])
- Ministerio de Ciencia e Innovación