Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions

TL;DR

This study provides numerical evidence for a deconfined quantum critical point in a 2D Heisenberg model with four-spin interactions, showing a continuous transition from Neel to VBS phase with emergent symmetry.

Contribution

It demonstrates that four-spin interactions can induce a deconfined quantum critical point in a 2D Heisenberg antiferromagnet, supported by quantum Monte Carlo simulations and finite-size scaling analysis.

Findings

Continuous transition with specific critical exponents

Emergent U(1) symmetry at the critical point

Strong evidence for deconfined quantum criticality

Abstract

Using ground-state projector quantum Monte Carlo simulations in the valence bond basis, it is demonstrated that non-frustrating four-spin interactions can destroy the Neel order of the two-dimensional S=1/2 Heisenberg antiferromagnet and drive it into a valence-bond solid (VBS) phase. Results for spin and dimer correlations are consistent with a single continuous transition, and all data exhibit finite-size scaling with a single set of exponents; z=1, nu=0.78 +/- 0.03, and eta=0.26 +/- 0.03. The unusually large eta and an emergent U(1) symmetry, detected using VBS order parameter histograms, provide strong evidence for a deconfined quantum critical point.