SU(6) Heisenberg model on the honeycomb lattice: competition between plaquette and chiral order

TL;DR

This study investigates the SU(6) Heisenberg model on the honeycomb lattice, revealing that the ground state favors a plaquette order over the previously predicted chiral spin liquid, with a phase transition induced by ring exchange interactions.

Contribution

The paper provides the first comprehensive numerical evidence favoring the plaquette state over the chiral spin liquid in the SU(6) Heisenberg model on the honeycomb lattice.

Findings

Plaquette state is energetically favored over chiral spin liquid.

A phase transition occurs between plaquette and chiral states with ring exchange.

Numerical methods confirm the stability of the plaquette order.

Abstract

We revisit the SU(6) Heisenberg model on the honeycomb lattice, which has been predicted to be a chiral spin liquid by mean-field theory [G. Szirmai et al., Phys. Rev. A 84, 011611 (2011)]. Using exact diagonalizations of finite clusters, infinite projected entangled pair states simulations, and variational Monte Carlo simulations based on Gutzwiller projected wave functions, we provide strong evidence in favour of the competing plaquette state, which was reported to be higher but close by in energy according to mean-field theory. This is further confirmed by the investigation of the model with a ring exchange term, which shows that there is a transition between the plaquette state and the chiral state at a finite value of the ring exchange term.