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Enhanced low-energy fluctuations and increasing out-of-plane coherence in vacancy-ordered Na_{x}CoO_{2}

Lemmens, P. and Gnezdilov, V. and Shu, G. J. and Alff, L. and Lin, C. T. and Keimer, B. and Chou, F. C. (2013):
Enhanced low-energy fluctuations and increasing out-of-plane coherence in vacancy-ordered Na_{x}CoO_{2}.
In: Physical Review B, American Physical Society, pp. 195151-5 (pp), 88, (19), ISSN 1098-0121,
[Online-Edition: http://dx.doi.org/10.1103/PhysRevB.88.195151],
[Article]

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.

Item Type: Article
Erschienen: 2013
Creators: Lemmens, P. and Gnezdilov, V. and Shu, G. J. and Alff, L. and Lin, C. T. and Keimer, B. and Chou, F. C.
Title: Enhanced low-energy fluctuations and increasing out-of-plane coherence in vacancy-ordered Na_{x}CoO_{2}
Language: English
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.

Journal or Publication Title: Physical Review B
Volume: 88
Number: 19
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 10 Jan 2014 11:17
Official URL: http://dx.doi.org/10.1103/PhysRevB.88.195151
Identification Number: doi:10.1103/PhysRevB.88.195151
Funders: This work was supported by Deutsche Forschungsgemeinschaft (DFG AL560/6, KE923/2, LE967/4).
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