Quantum Monte Carlo study of the attractive kagome-lattice Hubbard model

TL;DR

This study uses mean-field and quantum Monte Carlo methods to explore the attractive Hubbard model on the kagome lattice, revealing charge order and superconductivity phases that could explain experimental observations.

Contribution

It provides the first systematic investigation of the attractive kagome-lattice Hubbard model with both mean-field and determinant quantum Monte Carlo methods, identifying charge order and superconducting regions.

Findings

Charge-density-wave order satisfying the triangle rule predicted by mean-field.

s-wave superconductivity stabilized at low temperatures in dome regions.

Quantitative determination of superconducting critical temperature via finite-size scaling.

Abstract

Recent experimental discovery of several families of kagome-lattice materials has boosted the interest in electronic correlations on kagome lattice. As an initial step to understand the observed complex phenomena, it is helpful to know the correspondence between simple forms of interactions and the induced correlated states on kagome lattice. Considering the lack of such studies, here we systematically investigate the attractive kagome-lattice Hubbard model using the mean-field approach and determinant quantum Monte Carlo (DQMC). A charge-density-wave order satisfying the triangle rule is predicted by the mean-field treatment, and subsequent DQMC simulations provide indirect evidence for its existence. The $s$-wave superconductivity is found to be stabilized at low temperatures, and exists in dome regions of the phase diagrams. We then determine the superconducting critical temperature quantitatively by finite-size scaling of the pair structure factor. These results may be helpful in understanding the observed superconductivity in kagome-lattice materials.