2020/03/17 by Bowen Zhao, Jun Takahashi, Anders W. Sandvik
Physics and Astronomy · #Antiferromagnetism #Criticality #Merge (version control) #Phase transition #Physics of Superconductivity and Magnetism #Quantum #Quantum Monte Carlo #Quantum many-body systems #Quantum phase transition #Spinon #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1088/1674-1056/ab889b
published as Chin.Phys.B 29 (5), 057506 (2020) · 14 pages, 14 figures
arxiv created 2020/03/17 · openalex created_date 2020/03/23 · openalex publication_date 2020/04/12 · arxiv updated 2020/07/09 · openalex updated_date 2026/08/06
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 Z 4 symmetric cVBS order parameter when the transition is continuous. In contrast, when the transition changes to first-order, the clock-like Z 4 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.