Intermediate Haldane phase in spin-2 quantum chains with uniaxial anisotropy

TL;DR

This paper demonstrates the existence of an intermediate Haldane phase in spin-2 quantum chains with uniaxial anisotropy, using theoretical and numerical methods to characterize its properties and phase diagram.

Contribution

It identifies and characterizes an intermediate Haldane phase in a spin-2 chain, expanding understanding of quantum phase diagrams with uniaxial anisotropy.

Findings

Phase diagram includes SO(5) Haldane, intermediate Haldane, and large-D phases.

Edge states and string order parameters distinguish phases.

Entanglement spectrum degeneracies linked to symmetries.

Abstract

We provide evidence of an intermediate Haldane phase in a spin-2 quantum chain. By combining effective field theory and numerical approaches, we show that the phase diagram of the proposed model includes SO(5) Haldane, intermediate Haldane, and large-D phases. We determine the characteristic properties of these phases, including edge states, string order parameters, and degeneracies in the entanglement spectrum. The symmetries responsible for the degeneracy patterns observed in the entanglement spectrum are also discussed.