Tunable deconfined quantum criticality and interplay of different valence-bond solid phases
Files
Accepted manuscript
Date
2020-05
Authors
Zhao, Bowen
Takahashi, Jun
Sandvik, Anders W.
Version
Accepted manuscript
OA Version
Citation
Bowen Zhao, Jun Takahashi, Anders W Sandvik. 2020. "Tunable deconfined quantum criticality and interplay of different valence-bond solid phases." Chinese Physics B, Volume 29, Issue 5, pp. 057506 - 057506. https://doi.org/10.1088/1674-1056/ab889b
Abstract
We use quantum Monte Carlo simulations to study an S = 1/2 spin model with competing multi-spin interactions. We find a quantum phase transition between a columnar valence-bond solid (cVBS) and a Néel antiferromagnet (AFM), as in the scenario of deconfined quantum-critical points, as well as a transition between the AFM and a staggered valence-bond solid (sVBS). By continuously varying a parameter, the sVBS–AFM and AFM–cVBS boundaries merge into a direct sVBS–cVBS transition. Unlike previous models with putative deconfined AFM–cVBS transitions, e.g., the standard J–Q model, in our extended J–Q model with competing cVBS and sVBS inducing terms the transition can be tuned from continuous to first-order. We find the expected emergent U(1) symmetry of the microscopically Z4 symmetric cVBS order parameter when the transition is continuous. In contrast, when the transition changes to first-order, the clock-like Z4 fluctuations are absent and there is no emergent higher symmetry. We argue that the confined spinons in the sVBS phase are fracton-like. We also present results for an SU(3) symmetric model with a similar phase diagram. The new family of models can serve as a useful tool for further investigating open questions related to deconfined quantum criticality and its associated emergent symmetries.