Charge order and superconductivity in a two-dimensional triangular lattice at n=2/3

TL;DR

This study explores how charge order and potential superconductivity emerge in a doped two-dimensional triangular lattice modeled by the extended Hubbard model, revealing that Coulomb interactions induce specific charge and spin orders at certain fillings.

Contribution

It demonstrates the role of Coulomb interactions in inducing charge and spin order, and discusses the potential for superconductivity driven by charge fluctuations in a triangular lattice.

Findings

Coulomb interaction V induces honeycomb charge order at n=2/3.

Antiferromagnetic spin order appears at U>10t.

Charge fluctuations may lead to superconductivity.

Abstract

To investigate the possibility of charge order and superconductivity in a doped two-dimensional triangular lattice, we study the extended Hubbard model with variational Monte Carlo method. At n=2/3, a commensurate filling for a triangular lattice, it is shown that the nearest-neighbor Coulomb interaction V induces honeycomb-type charge order and antiferromagnetic spin order at U>10t. We also discuss the possibility of superconductivity induced by charge fluctuation and the relation to the superconductivity in Na_{0.35}CoO_{2}1.3H_{2}O and theta-type organic condoctors.