Spontaneous dimerization in the spin-1 bilinear-biquadratic Heisenberg model on a honeycomb lattice

TL;DR

This paper demonstrates that the spin-1 bilinear-biquadratic Heisenberg model on a honeycomb lattice can spontaneously form a columnar dimer order due to quantum fluctuations, with distinct excitations and a potential first-order phase transition.

Contribution

It reveals a novel dimerized ground state induced by quantum order-by-disorder in the model on a honeycomb lattice, analyzed via linear flavor-wave theory.

Findings

Spontaneous columnar dimer order identified

Flat bands of excitations with energy gaps observed

First-order quantum phase transition suggested

Abstract

Within the linear flavor-wave theory, we show that, caused by quantum order-by-disorder mechanism, the spin-1 bilinear-biquadratic Heisenberg model defined on a honeycomb lattice can spontaneously develop a columnar dimer order with a non-bipartite structure. The low-lying excitations above this novel ground state form several flat bands separated by nonzero energy gaps. Our results suggest that the quantum phase transition separating this dimerized phase with the nearby N\'{e}el-order one may be of first order.