Multiorbital kinetic effects on charge ordering of frustrated electrons on the triangular lattice

TL;DR

This study explores how multiorbital effects influence charge ordering in frustrated electrons on a triangular lattice, revealing a rich phase diagram with unconventional phases driven by Coulomb interactions and orbital anisotropy.

Contribution

It demonstrates the emergence of novel electronic phases due to multiorbital effects in a frustrated lattice, extending understanding beyond single-band models.

Findings

Identification of three unconventional phases: pinball liquid, inverse pinball liquid, and droplet phase.

Phase stability depends on Coulomb interactions and orbital hopping anisotropy.

The model recovers standard Hubbard behavior in the isotropic limit.

Abstract

The role of the multiorbital effects on the emergence of frustrated electronic orders on the triangular lattice at half filling is investigated through an extended spinless fermion Hubbard model. By using two complementary approaches, unrestricted Hartree-Fock and exact diagonalizations, we unravel a very rich phase diagram controlled by the strength of both local and off-site Coulomb interactions and by the interorbital hopping anisotropy ratio $t'/t$. Three robust unconventional electronic phases, a pinball liquid, an inverse pinball liquid, and a large-unit-cell $\sqrt{12} \times \sqrt{12}$ droplet phase, are found to be generic in the triangular geometry, being controlled by the band structure parameters. The latter are also stabilized in the isotropic limit of our microscopic model, which recovers the standard SU(2) spinful extended single-band Hubbard model.