Orbital current patterns in doped two-leg Cu-O Hubbard ladders

TL;DR

This paper studies doped two-leg Cu-O Hubbard ladders, revealing a quantum critical regime and orbital current patterns using bosonization, with implications for NMR properties across different phases.

Contribution

It introduces a detailed analysis of orbital current patterns and quantum critical behavior in doped Cu-O ladders, extending understanding beyond single orbital models.

Findings

Existence of a massless quantum critical regime at certain doping levels

Presence of orbital current patterns coexisting with density waves

Predictions for NMR signatures of different phases

Abstract

In the weak coupling limit, we investigate two-leg ladders with a unit cell containing both Cu and O atoms, as a function of doping. For purely repulsive interactions, using bosonization, we find significant differences with the single orbital case: a completely massless quantum critical regime is obtained for a finite range of carrier concentration. In a broad region of the phase diagram the ground state consists of a pattern of orbital currents plus a density wave. NMR properties of the Cu and O nuclei are presented for the various phases.