Novel coexisting density wave ground state in strongly correlated, two-dimensional electronic materials

TL;DR

This paper reports the discovery of a new insulating bond-order/charge density wave state in strongly correlated 2D electronic materials, persisting across all anisotropies and challenging non-interacting electron predictions.

Contribution

It introduces a novel density wave ground state in 2D strongly correlated systems, emphasizing the role of electron-electron interactions and confinement.

Findings

Identification of a persistent BCDW state in 2D materials

Explanation of coexistence of density waves in organic solids

Insights into optical conductivity and organic superconductivity

Abstract

Two-dimensional (2D) strongly correlated electron systems underlie many of the most important phenomena in contemporary condensed matter physics, including the Quantum Hall Effect (QHE), ``high T_c'' superconductivity, and possible exotic conducting states in silicon MOSFETs. We demonstrate the existence of yet another exotic ground state in strongly correlated, 2D electronic materials: a novel, insulating bond-order/charge density wave state (BCDW) in the commensurate 1/4-filled band that persists for all anisotropies within the 2D lattice, in contradiction to the non-interacting electron prediction of the vanishing of density waves in 2D for non-1/2-filled bands. The persistence of the BCDW in the 2D lattice is a consequence of strong electron-electron (e-e) interaction and the resultant ``confinement,'' a concept recently widely debated. Our results have implications for experiments in the organic charge transfer solids (CTS), where they explain the observation of a ``mysterious'' coexistence of density waves, clarify the optical conductivity of the ``metallic'', and suggest an approach to the observed organic superconductivity.