Transport and pressure properties of single crystals with metallic ground stateG. Garbarino1, F. Morales1, M. Núñez Regueiro1, M. Armand2 and P. Lejay1
1 Institut NEEL, CNRS and Université Joseph Fourier - BP 166 Bât E, F-38042 Grenoble Cedex 9, France
2 Laboratoire réactivité et chimie des solides (LRCS), Université Picardie Jules-Verne Amiens - 33, Rue Saint-Leu, F-80039 Amiens Cedex 1, France
received 24 October 2007; accepted in final form 18 December 2007; published February 2008
published online 22 January 2008
We report transport properties as a function of temperature and pressure up to 16 GPa in single crystals of NaxCoO2. Our x = 0.5- samples, obtained by a novel de-intercalation method, present the transitions characteristic of x = 0.5 samples, albeit with a metallic ground state at low temperatures. Besides the obvious consequences of the sub-stoichiometry of our samples, we present evidence suggesting that an insulator state can be induced by disorder that localizes the few carriers left after the transitions.
72.80.Ga - Transition-metal compounds.
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
62.50.+p - High-pressure and shock wave effects in solids and liquids.
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