Deconfined pseudocriticality in a model spin-1 quantum antiferromagnet

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Statistical Mechanics

Background:

• Deconfined quantum criticality (DQC) theory, based on Berry phase interference, explains continuous transitions in S=1/2 antiferromagnets.
• This theory has been extended to S=1 magnets, proposing continuous Néel to columnar valence bond solid (cVBS) transitions.

Purpose of the Study:

• To explore a microscopic model for continuous transitions in S=1 magnets.
• To investigate the nature of the Néel to cVBS transition in a specific square lattice model.

Main Methods:

• Developed a square lattice model with Heisenberg (J H), biquadratic (J B), and Q-term (Q B) interactions.
• Employed large-scale quantum Monte Carlo (QMC) simulations to analyze the model's behavior.
• Utilized Binder analysis and order parameter histograms to characterize critical phenomena.

Main Results:

• For J H = 0, the model mirrors the SU(3) JQ model, exhibiting a DQC-like Néel-cVBS transition.
• Introducing J H (reducing symmetry to SU(2)) showed signatures suggestive of a continuous transition.
• Binder analysis revealed sub-extensive negative dips, indicating pseudocritical behavior rather than a true continuous transition.

Conclusions:

• The studied Néel-cVBS transition in the S=1 model is interpreted as pseudocritical.
• Deconfined pseudocriticality appears to be a more prevalent scenario than previously thought, even in S=1 systems.
• Findings align with recent studies on spin-1/2 models, reinforcing the prevalence of pseudocriticality.