Raman Phonons and Ageing-Related Surface Disorder in NaxCoO2

Abstract

The polarized Raman spectra from ab and ac surfaces of single crystal NaxCoO2 (x~0.7), parent compound of recently discovered superconductor NaxCoO2.yH2O, are reported and discussed. The crystals were hexagon platelets of typical size 3x3x0.1 mm. Three of the five (A1g+E1g+3E2g) Raman active phonons were unambiguously identified at 458 (E1g), 494(E2g) and 574 (A1g) cm-1. The spectra from ab and ac surfaces differ significantly and provide evidence that within hours after preparation the ac surface, unlike the ab one, is strongly disordered. Within several days the disorder extends over the ab surface too.

arXiv comment4 pages, 1 table, 4 figures. Physica C (accepted 26 September 2003)

References in corpus (2)

• An Electronic Model for $Co{O}_2$ layer based systems: Chiral RVB metal and Superconductivity
• Effect of Na content and hydration on the excitation spectrum of the cobaltite Na_xCoO_2 yH_2O

Cited by in corpus (18)

• Doping effects on the electronic and structural properties of CoO2: An LSDA+U study
• Raman spectroscopy study of NaxCoO2 and superconducting NaxCoO2.yH2O
• Anomalous electronic Raman scattering in Na_xCoO_2 H_2O
• Raman Spectroscopy Study of alpha-, beta-, gamma-NaxCoO2 and gamma-(Ca,Sr)xCoO2
• Anisotropic quasiparticle renormalization in Na0.73CoO2: role of inter-orbital interactions and magnetic correlations
• First principles lattice dynamics of NaCoO${}_2$
• X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2
• Effect of Na content and hydration on the excitation spectrum of the cobaltite Na_xCoO_2 yH_2O
• Stripe correlations in Na${}_{0.75}$CoO${}_2$
• Study of intercalation and deintercalation of Na_xCoO_2 yH_2O single crystals
• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system
• Optical evidence for the proximity to a spin-density-wave metallic state in Na${}_{0.7}$CoO${}_2$
• Electron-phonon interaction in the lamellar cobaltate Na${}_x$CoO${}_2$
• Phonon scattering and stability of Na_0.5CoO_2
• Comment on "Raman spectroscopy study of NaxCoO2 and superconducting NaxCoO2 yH2O"
• Phonon softening and "forbidden" mode observed by Raman scattering in Na0.5CoO2
• Nature of Correlated Motion of Electrons in the Parent Cobaltate Superconductors
• Enhanced low energy fluctuations and increasing out-of-plane coherence in vacancy ordered NaxCoO2