Weak-Coupling Approach to Hole-Doped S=1 Haldane Systems

TL;DR

This paper investigates weak-coupling models of hole-doped S=1 Haldane systems using bosonization and RG methods, revealing how disorder influences the stability of the Tomonaga-Luttinger liquid state.

Contribution

It introduces and analyzes two weak-coupling models for hole-doped S=1 Haldane systems, highlighting the role of disorder in stabilizing certain quantum states.

Findings

Disorder suppresses Anderson localization in the models.

The Tomonaga-Luttinger liquid state with a spin gap is stabilized by weak randomness.

Fixed point properties are characterized using bosonization and RG analysis.

Abstract

As a weak-coupling analogue of hole-doped $S=1$ Haldane systems, we study two models for coupled chains via Hund coupling; coupled Hubbard chains, and a Hubbard chain coupled with an $S=1/2$ Heisenberg chain. The fixed point properties of these models are investigated by using bosonization and renormalization group methods. The effect of randomness on these fixed points is also studied. It is found that the presence of the disorder parameter inherent in the Haldane state in the former model suppresses the Anderson localization for weak randomness, and stabilizes the Tomonaga-Luttinger liquid state with the spin gap.