Quantum spin liquid in antiferromagnetic chain S=1/2 with Acoustic Phonons

TL;DR

This paper investigates the effects of nonadiabatic acoustic phonons on a quantum antiferromagnetic S=1/2 chain, revealing a critical coupling for gap opening and explaining properties of CuGeO3 without spin-Peierls transition.

Contribution

It introduces a nonadiabatic quantum Monte Carlo analysis of spin-phonon interactions in S=1/2 chains, identifying phase boundaries and symmetry breaking effects.

Findings

Critical coupling induces a gap in triplet excitations.

Phase boundaries for phonon delocalization and bound states are determined.

Spherical symmetry of spin correlations is broken, explaining CuGeO3 properties.

Abstract

A spin and phonon excitations spectrum are studied using quantum Monte Carlo method in antiferromagnetic chain with spins $S=1/2$ coupled nonadiabaticity with acoustic phonons . It is found the critical coupling exists to open gap in the triplet excitation spectrum for any phonon velocity. The phase boundaries of delocalized phonons and propagated the bound states of magnon and a phonon are calculated. It is shown that the spherical symmetry of the spin-spin correlation functions is broken . The magnetic and optical properties $CuGeO_3$ are explained without using spin-Peierls transition.