Field-induced structural evolution in the spin-Peierls compound CuGeO$_3$: high-field ESR study

TL;DR

This study uses high-field ESR to investigate the structural evolution and soliton-like phase transition in the spin-Peierls compound CuGeO$_3$, revealing field-induced incommensurate structures and effects of doping on soliton states.

Contribution

It provides new insights into the field-induced incommensurate phase and the impact of doping on soliton states in CuGeO$_3$ using high-resolution ESR.

Findings

ESR linewidth increases with magnetic field, indicating soliton development

Soliton-like phase exists near the phase transition boundary

Doping suppresses the soliton-related ESR anomaly

Abstract

The dimerized-incommensurate phase transition in the spin-Peierls compound CuGeO$_3$ is probed using multifrequency high-resolution electron spin resonance (ESR) technique, in magnetic fields up to 17 T. A field-induced development of the soliton-like incommensurate superstructure is clearly indicated as a pronounced increase of the ESR linewidth $\Delta B$ (magnon excitations), with a $\Delta B_{max}$ at $B_{c}\sim$ 13.8 T. The anomaly is explained in terms of the magnon-soliton scattering, and suggests that the soliton-like phase exists close to the boundary of the dimerized-incommensurate phase transition. In addition, magnetic excitation spectra in 0.8% Si-doped CuGeO$_3$ are studied. Suppression of the $\Delta B$ anomaly observed in the doped samples suggests a collapse of the long-range-ordered soliton states upon doping, that is consistent with high-field neutron scattering experiments.