Strong coupling theory of the spinless charges on the triangular lattices: possibility of a new quantum liquid

TL;DR

This paper introduces a novel charge liquid state called the 'pinball liquid' in spinless fermion systems on triangular lattices, arising from strong Coulomb interactions and geometrical frustration, with implications for organic materials.

Contribution

It proposes the 'pinball liquid' as a new quantum liquid phase resulting from the interplay of strong interactions and frustration in triangular lattice systems.

Findings

Identification of a 'pinball liquid' phase in the strong coupling limit.

Coexistence of Wigner crystal and liquid components in the system.

Relevance of the model to organic theta-ET_2X materials.

Abstract

We propose a new type of charge liquid state in the spinless fermion system on a triangular lattice under strong inter-site Coulomb interactions, $V$. In the strong coupling limit ($t=0$), the ground state is classical and disordered due to geometrical frustration. The introduction of small t will drive the system to a partially ordered phase which we call a "pinball liquid". A possibly long range ordered Wigner crystal solid coexist with a liquid component which are moving around them like a pinball. This liquid is dominant over wide range of filling, even away from the regular triangle, and is also realized in the hard core boson systems. Relevance to the organic theta-ET_2X is discsussed.