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Non-magnetic insulator state in Na1CoO2 and phase separation of Na vacancies

C. de Vaulx·M. -H. Julien·C. Berthier·M. Horvatic·P. Bordet·V. Simonet·D. P. Chen·C. T. Lin
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Abstract

Crystallographic, magnetic and NMR properties of a NaxCoO2 single crystal with x~1 are presented. We identify the stoichiometric Na1CoO2 phase, which is shown to be a non-magnetic insulator, as expected for homogeneous planes of Co3+ ions with S=0. In addition, we present evidence that, because of slight average Na deficiency, chemical and electronic phase separation leads to a segregation of Na vacancies into the well-defined, magnetic, Na0.8CoO2 phase. The importance of phase separation is discussed in the context of magnetic order for x~0.8 and the occurrence of a metal-insulator transition for x->1.

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C. de Vaulx, M. -H. Julien, C. Berthier, M. Horvatic, P. Bordet, V. Simonet, D. P. Chen, C. T. Lin. 2005-09-13. Non-magnetic insulator state in Na1CoO2 and phase separation of Na vacancies. https://doi.org/10.1103/physrevlett.95.186405

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