Charge bond order and s-wave superconductivity in the kagome lattice with electron-phonon coupling and electron-electron interaction

Abstract

The effects of optical bond phonons coupled to electrons in two-dimensional lattices have attracted much interest recently, with the hope to explore unconventional superconducting mechanism and pairing symmetries. Here we conduct a systematic investigation of such phonon modes in the kagome lattice at and around the upper van Hove filling, in order to unravel new effects of the bond phonons in the presence of the unique sublattice frustration. We combine the singular-mode functional renormalization group and the projector determinant quantum Monte Carlo methods. At the upper van Hove filling and in the absence of the Hubbard interaction $U$, we find there exists an s-wave superconducting state at weaker electron-phonon coupling constant $\lambda$ and higher phonon frequency $\omega$, and a charge bond order (or the valence bond solid) state at larger $\lambda$ and lower $\omega$. The Hubbard interaction $U$ suppresses drastically the s-wave pairing, so that only the charge bond order survives. On the other hand, upon slight doping away from the van Hove filling, we observe that the charge bond order is suppressed due to the breakdown of the perfect Fermi surface nesting, while the superconductivity persists. The s-wave superconductivity and charge bond order may be relevant in the layered kagome superconductors AV${}_3$Sb${}_5$ (A=K, Rb, Cs).

References in corpus (17)

• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice
• Topological kagome magnets and superconductors
• Unconventional Fermi surface instabilities in the Kagome Hubbard Model
• Superconductivity in the ${\mathbb{Z}}_2$ kagome metal KV${}_3$Sb${}_5$
• Superconductivity and normal-state properties of kagome metal RbV3Sb5 single crystals
• Ground State of the Kagome Lattice Heisenberg Antiferromagnet
• Possible $S_{\pm }$-wave superconductivity in La${}_3$Ni${}_2$O${}_7$
• Applications of quantum Monte Carlo methods in condensed systems
• Variational Monte Carlo study of chiral spin liquid in the extended Heisenberg model on the Kagome lattice
• Novel magnetic orderings in the kagome Kondo-lattice model
• Kinetic ferromagnetism on a kagome lattice
• Exchange-biased topological transverse thermoelectric effects in a Kagome ferrimagnet
• Pinch-points to half-moons and up in the stars: the kagome skymap
• Kagome qubit ice
• A functional renormalization group study of the two dimensional Su-Schrieffer-Heeger-Hubbard model
• Matrix element interference in $N$-patch functional renormalization group

Cited by in corpus (4)

• The kagome Hubbard model from a functional renormalization group perspective
• Self-consistent theory of $2\times 2$ pair density waves in kagome superconductors
• Exotic charge density waves and superconductivity on the Kagome Lattice
• Topological Aspects of Dirac Fermions in a Kagomé Lattice