Charge Density Waves and the Hidden Nesting of Purple Bronze K$_{0.9}$Mo$_6$O$_{17}$

TL;DR

This paper develops a multiorbital tight-binding model for K$_{0.9}$Mo$_6$O$_{17}$ that accurately reproduces charge density wave phenomena and Fermi surface features observed experimentally, highlighting the role of electron-electron interactions.

Contribution

It introduces the first multiorbital effective model for this system and demonstrates its success in matching experimental CDW behavior using a self-consistent Hartree-Fock approach.

Findings

Model reproduces the CDW order parameter across all temperatures below T_c.

Accurately predicts the reciprocal space locations of partial gaps and Fermi arcs.

Interaction strengths are consistent with independent theoretical estimates.

Abstract

We introduce the first multiorbital effective tight-binding model to describe the effect of electron-electron interactions in this system. Upon fixing all the effective hopping parameters in the normal state against an ab initio band structure, and with only the overall scale of the interactions as the sole adjustable parameter, we find that a self-consistent Hartree-Fock solution reproduces extremely well the experimental behavior of the charge density wave (CDW) order parameter in the full range $0<T<T_{\text{c}}$, as well as the precise reciprocal space locations of the partial gap opening and Fermi arc development. The interaction strengths extracted from fitting to the experimental CDW gap are consistent with those derived from an independent Stoner-type analysis.