Cluster quantum Monte Carlo study of two-dimensional weakly-coupled frustrated trimer antiferromagnets

TL;DR

This study uses cluster quantum Monte Carlo simulations to analyze thermodynamic properties of two-dimensional frustrated quantum antiferromagnets composed of weakly-coupled spin-1/2 trimers, revealing insights into specific heat behavior and chiral order.

Contribution

It introduces a trimer-based computational basis that reduces the sign problem in quantum Monte Carlo simulations of frustrated antiferromagnets.

Findings

Reduced sign problem enables low-temperature simulations.

Observed two-peak specific heat structure in kagome lattice.

Assessed mean field predictions for chiral order onset.

Abstract

We report results from spin trimer-based cluster quantum Monte Carlo simulations for the thermodynamic properties of two-dimensional frustrated quantum antiferromagnets that are composed of weakly-coupled three-spin (trimer) clusters. In particular, we consider the spin-1/2 kagome lattice with a strong breathing distortion, and the triangle-square lattice model proposed previously for the cuprate La${}_4$Cu${}_3$MoO${}_{12}$. For both cases, we demonstrate that an appropriately chosen trimer-based computational basis allows us to significantly reduce the quantum Monte Carlo sign problem down to the low-temperature regime. Besides exploring the thermodynamic behavior for the triangle-square lattice model we also assess a mean field theory-based prediction for the onset of chiral order. For the breathing distorted kagome lattice model, we observe a robust two-peak structure in the specific heat, both in the quantum spin liquid and the lattice-nematic regimes.