Enhanced low-energy fluctuations and increasing out-of-plane coherence in vacancy-ordered NaxCoO2
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
88
Journal Issue
19
Date Issued
2013
Author(s)
Abstract
We report Raman scattering experiments on the strongly correlated electron system NaxCoO2 with x = 0.71 and ordered Na vacancies. This phase exhibits unusual transport and thermodynamic properties. Furthermore, hydrated samples with the same Co valency are superconducting. Our Raman scattering data reveal pronounced low-energy fluctuations that diverge in intensity at low temperatures. There is a related decrease of the electronic scattering rate Γ from 50 to 3 cm-1. Simultaneous with the evolution of the scattering rate, phonon anomalies point to an increasing out-of-plane coherence of the lattice with decreasing temperature. These observations may indicate the condensation of spin polarons into an unusual, highly dynamic ground state. © 2013 American Physical Society.
SDGs
Type
journal article