Correlation-driven chiral superconductivity and chiral spin order in doped kagome lattice

TL;DR

This paper investigates the electronic instabilities in a doped kagome lattice Hubbard model, revealing conditions for chiral superconductivity, chiral spin order, and a spin-disordered insulator, using the variational cluster approach.

Contribution

It demonstrates the emergence of chiral superconductivity and chiral spin order in the doped kagome lattice, highlighting the role of electron interactions and Fermi surface properties.

Findings

Chiral d+id superconductivity is favored at small Hubbard U.

Scalar chiral spin order appears at large U.

A spin-disordered insulating state exists between these phases.

Abstract

We study the electronic instabilities of the Hubbard model in the 1/6 hole-doped Kagome lattice using the variational cluster approach. The 1/6 hole doping is unique in the sense that the Fermi level is at the von Hove singularity and the Fermi surface has a perfect nesting. In this case, a density wave is usually realized. However, we demonstrate here that the chiral $d_{x^{2}-y^{2}}+id_{xy}$ superconducting state is most favorable when a small Hubbard interaction U(U<3.0t) is introduced, and a scalar chiral spin order is realized at large U(U>5.0t). Between them, a spin-disordered insulating state is proposed.