Critical Properties of the transition between the Haldane phase and the large-D phase of the spin-1/2 ferromagnetic-antiferromagnetic Heisenberg chain with on-site anisotropy"

TL;DR

This paper analytically investigates the quantum phase transition between the Haldane and large-D phases in an anisotropic spin-1/2 chain, revealing continuous variation of critical exponents through bosonization.

Contribution

It introduces a generalized model and applies bosonization to analytically characterize the critical properties of the Haldane-LD transition, including critical exponent behavior.

Findings

Critical exponents vary continuously on the phase boundary.

Scaling relations accurately explain numerical results.

The model transformation elucidates the competition between bond alternations.

Abstract

We analytically study the ground-state quantum phase transition between the Haldane phase and the large-$D$ (LD) phase of the $S=1/2$ ferromagnetic-antiferromagnetic alternating Heisenberg chain with on-site anisotropy. We transform this model into a generalized version of the alternating antiferromagnetic Heisenberg model with anisotropy. In the transformed model, the competition between the transverse and longitudinal bond alternations yields the Haldane-LD transition. Using the bosonization method, we show that the critical exponents vary continuously on the Haldane-LD boundary. Our scaling relations between critical exponents very well explains the numerical results by Hida.