Charge ordering in quasi-one-dimensional systems with frustrating interactions

TL;DR

This paper investigates charge and spin ordering phenomena in a coupled two-leg ladder system using a pseudospin model, revealing a complex phase diagram with various ordered and gapless phases relevant to strongly correlated materials.

Contribution

It introduces a comprehensive pseudospin model analysis for ladder systems, identifying multiple phases including charge order, spin order, and an orbital antiferromagnetic phase, with a focus on the stability of these phases.

Findings

Identification of Wigner/Peierls charge order

Discovery of a stable orbital antiferromagnetic phase

Existence of an intermediate gapless phase

Abstract

Motivated by the co-existing charge and spin order found in strongly correlated ladder systems, we study an effective pseudospin model on a coupled two-leg ladder. A bosonisation analysis yields a rich phase diagram showing Wigner/Peierls charge order and Neel/dimer spin order. In a broad parameter regime, the orbital antiferromagnetic phase is found to be stable. An intermediate gapless phase of finite width is found to lie in between two charge-ordered gapped phases. Our work is potentially relevant for a unified description of a class of strongly correlated, quarter-filled ladder systems.