Thermodynamic signature of the $\mathrm{SU}(4)$ spin-orbital liquid and symmetry fractionalization from the Lieb-Schultz-Mattis theorem

TL;DR

This study investigates the thermodynamic properties of the $ ext{SU}(4)$ Heisenberg model on the honeycomb lattice, revealing features indicative of a quantum spin-orbital liquid phase and discussing implications of symmetry and gapped ground states.

Contribution

First large-scale finite-temperature simulation of the $ ext{SU}(4)$ Heisenberg model on the honeycomb lattice using the thermal pure quantum state method, capturing thermodynamic signatures of the spin-orbital liquid.

Findings

Specific heat exhibits a peak-and-shoulder structure.

Thermodynamic behavior consistent with a quantum spin-orbital liquid.

Discussion on symmetry and gapped ground state implications.

Abstract

The $\mathrm{SU}(4)$ Heisenberg model on the honeycomb lattice is expected to host a quantum spin-orbital liquid at low temperature with an astonishing candidate material, $\alpha$-ZrCl$_3$. We employed the canonical thermal pure quantum state method to investigate the finite-temperature phase of this model. Exploiting the full symmetry of $\mathrm{SU}(4)$, the calculation up to a 24-site cluster, which is equivalent to 48 sites in the spin-1/2 language, is possible. This state-of-the-art computation with large-scale parallelization enables us to capture the thermodynamic properties of the $\mathrm{SU}(4)$ Heisenberg model on the honeycomb lattice. In particular, the specific heat shows a characteristic peak-and-shoulder structure, which should be related to the nature of the low-temperature quantum spin-orbital liquid phase. We also discuss what can be concluded from the assumption that the ground state is gapped and symmetric in view of the generalized Lieb-Schultz-Mattis theorem.