NMR study of the anomalous metallic state below the CDW transition temperature in Rb3Cu8S6: A possibility of self-organized spinless solitons.

Abstract

The anomalous metallic state below the charge-density-wave (CDW) transition temperature of ${\mathrm{Rb}}_{3}$${\mathrm{Cu}}_{8}$${\mathrm{S}}_{6}$ has been studied by NMR. This compound shows metal-CDW-metal transitions at $110 \mathrm{K}({T}_{c1})$ and $50 \mathrm{K}({T}_{c2})$, respectively. In the Cu spectra below ${T}_{c2}$, a broad hump appears just between two peaks of the double-horned spectrum characteristic for CDW states, indicating the existence of domain walls on the CDW chains. On the other hand, Rb spectra suggest that the electronic states of the Rb sites slightly change below ${T}_{c2}$. This may reflect a small change in the electronic states of the Cu-S planes where CDW's develop, and suggests a possibility that the domain walls might act as spinless solitons, as is observed in polyacetylene chains.