Magnetic Excitations in quasi two-dimensional Spin-Peierls Systems

TL;DR

This paper models a two-dimensional frustrated quantum spin system to understand magnetic excitations, successfully matching experimental neutron scattering data and revealing a high-energy continuum in the dynamic structure factor.

Contribution

It introduces a bond-boson approach to analyze quantum disorder and elementary excitations in a spin-Peierls system, providing new insights into the dispersion and continuum features.

Findings

Triplet dispersion matches neutron scattering data

High-energy continuum observed in the dynamic structure factor

Ground state energy and spin gap characterized

Abstract

A study is presented of a two-dimensional frustrated and dimerized quantum spin-system which models the effect of inter-chain coupling in a spin-Peierls compound. Employing a bond-boson method to account for quantum disorder in the ground state the elementary excitations are evaluated in terms of gapful triplet modes. Results for the ground state energy and the spin gap are discussed. The triplet dispersion is found to be in excellent agreement with inelastic neutron scattering data in the dimerized phase of the spin-Peierls compound CuGeO_3. Moreover, consistent with these neutron scattering experiments, the low-temperature dynamic structure factor exhibits a high-energy continuum split off from the elementary triplet mode.