Domain excitations in spin-Peierls systems

TL;DR

This paper investigates the excitation spectrum of a Spin-Peierls system modeled by coupled antiferromagnetic chains, revealing localized domain excitations with energies below the magnon gap, relevant to experimental observations.

Contribution

It introduces a bosonization and self-harmonic approximation analysis of domain excitations in Spin-Peierls systems, highlighting localized triplet states with lower formation energy.

Findings

Localized domain excitations are triplet states with energies below the magnon gap.

Formation of localized domains involves opposite dimerized order.

Results align with experimental data on CuGeO₃.

Abstract

We study a model of a Spin-Peierls material consisting of a set of antiferromagnetic Heisenberg chains coupled with phonons and interacting among them via an inter-chain elastic coupling. The excitation spectrum is analyzed by bosonization techniques and the self-harmonic approximation. The elementary excitation is the creation of a localized domain structure where the dimerized order is the opposite to the one of the surroundings. It is a triplet excitation whose formation energy is smaller than the magnon gap. Magnetic internal excitations of the domain are possible and give the further excitations of the system. We discuss these results in the context of recent experimental measurements on the inorganic Spin-Peierls compound CuGeO$_3$