Quantum Phase Transition in Antiferromagnetic Heisenberg Chains Coupled to Phonons

TL;DR

This paper presents an analytical method to study quantum phase transitions in antiferromagnetic Heisenberg chains coupled to phonons, revealing a new transition driven by the geometry of the spin-phonon interaction.

Contribution

It introduces a novel analytical approach and uncovers a previously unknown quantum phase transition induced by the geometrical structure of the interaction.

Findings

Identifies a new quantum phase transition at zero temperature.

Shows the transition is driven by the geometry of the spin-phonon coupling.

Relates the magnetic properties to known transitions in frustrated models.

Abstract

We develop an analytical approach based on a unitary transformation to investigate S=1/2 antiferromagnetic Heisenberg chains coupled to phonons, and find a new quantum phase transition at zero temperature. Although the usual phase transition occurs depending on the strengths of the spin-spin and spin-phonon interactions, the phase transition in the present work is induced by a change in the geometrical structure of the spin-phonon interaction. The magnetic properties of the phase transition can be understood in relation to a phase transition that has already been found in the frustrated J1-J2 model.