TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.2.061
TI  - Diagnosing weakly first-order phase transitions by coupling to order parameters
PY  - 2023/08/14
UR  - https://scipost.org/SciPostPhys.15.2.061
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 2
SP  - 061
A1  - D'Emidio, Jonathan
AU  - Eberharter, Alexander
AU  - Läuchli, Andreas
AB  - 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.
ER  -

@Article{10.21468/SciPostPhys.15.2.061,
	title={{Diagnosing weakly first-order phase transitions by coupling to order parameters}},
	author={Jonathan D'Emidio and Alexander A. Eberharter and Andreas M. Läuchli},
	journal={SciPost Phys.},
	volume={15},
	pages={061},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.2.061},
	url={https://scipost.org/10.21468/SciPostPhys.15.2.061},
}