Sublattice modulated superconductivity in the Kagome Hubbard model

TL;DR

This paper uncovers a novel sublattice modulated superconducting state on the kagome lattice, characterized by intra-unit cell pairing modulations and symmetry breaking, analyzed through functional renormalization group methods.

Contribution

It introduces and characterizes a new sublattice modulated superconducting phase in the kagome Hubbard model, detailing its emergence and properties via a microscopic approach.

Findings

Identification of a sublattice modulated superconducting state with intra-unit cell pairing modulations.

Demonstration of the coexistence and competition between this state and d-wave superconductivity.

Discovery of a vestigial charge density wave and s-wave superconductivity near the modulated phase.

Abstract

We identify a superconducting order featuring spatial pair modulations on the kagome lattice subject to onsite Hubbard U and nearest neighbor V interactions. Within our functional renormalization group analysis, this state appears with a concomitant d-wave superconducting (SC) instability at zero lattice momentum, where it distinguishes itself through intra-unit cell modulations of the pairing function thus breaking the discrete space group symmetry. The relative weight of the sublattice modulated superconductor (SMS) and d-wave SC is influenced by the absolute interaction strength and coupling ratio V /U . Parametrically adjacent to this domain at weak coupling, we find an intra-unit cell modulated vestigial charge density wave and an s-wave SC instability. Our study provides a microscopic setting and thorough description of this novel SMS arising within a translation symmetry broken background.