Neutron and X-ray Scattering Studies of the Lightly-Doped Spin-Peierls System Cu(1-x)Cd(x)GeO3

TL;DR

This study investigates the magnetic excitation spectrum of lightly-doped Cu(1-x)Cd(x)GeO3 using neutron and X-ray scattering, revealing a finite triplet gap at the spin-Peierls transition.

Contribution

It provides new insights into the relation between the triplet gap and spin-Peierls order in a doped quantum antiferromagnet, using multiple experimental techniques and theoretical models.

Findings

Finite triplet gap exists at the phase transition

Sensitivity of gap energy to theoretical modeling

Correlation between gap and dimerisation order

Abstract

Single crystals of the lightly-doped spin-Peierls system Cu(1-x)Cd(x)GeO3 have been studied using bulk susceptibility, x-ray diffraction, and inelastic neutron scattering techniques. We investigate the triplet gap in the magnetic excitation spectrum of this quasi-one dimensional quantum antiferromagnet, and its relation to the spin-Peierls dimerisation order parameter. We employ two different theoretical forms to model the inelastic neutron scattering cross section and chi''(Q,omega), and show the sensitivity of the gap energy to the choice of chi''(Q,omega). We find that a finite gap exists at the spin-Peierls phase transition.