Phase diagram of hole doped two-leg Cu-O ladders

TL;DR

This paper maps the phase diagram of hole-doped two-leg Cu-O ladders using bosonization and RG techniques, revealing a massless quantum critical region with complex orbital and spin orderings.

Contribution

It introduces a detailed phase diagram for Cu-O ladders considering both Cu and O atoms, highlighting differences from single orbital models.

Findings

Massless quantum critical region at intermediate doping

Incommensurate orbital current patterns

Spin density wave structures

Abstract

In the weak coupling limit, we establish the phase diagram of a two-leg ladder with a unit cell containing both Cu and O atoms, as a function of doping. We use bosonization and design a specific RG procedure to handle the additional degrees of freedom. Significant differences are found with the single orbital case; for purely repulsive interactions, a completely massless quantum critical region is obtained at intermediate carrier concentrations (well inside the bands) where the ground state consists of an incommensurate pattern of orbital currents plus a spin density wave (SDW) structure.