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arXiv · 0909.3556

Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0)

T. Motohashi·T. Ono·Y. Sugimoto·Y. Masubuchi·S. Kikkawa·R. Kanno·M. Karppinen·H. Yamauchi
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Abstract

Here we report the magnetic properties of the layered cobalt oxide system, LixCoO2, in the whole range of Li composition, 0 <= x <= 1. Based on dc-magnetic susceptibility data, combined with results of 59Co-NMR/NQR observations, the electronic phase diagram of LixCoO2 has been established. As in the related material NaxCoO2, a magnetic critical point is found to exist between x = 0.35 and 0.40, which separates a Pauli-paramagnetic and a Curie-Weiss metals. In the Pauli-paramagnetic regime (x <= 0.35), the antiferromagnetic spin correlations systematically increase with decreasing x. Nevertheless, CoO2, the x = 0 end member is a non-correlated metal in the whole temperature range studied. In the Curie-Weiss regime (x >= 0.40), on the other hand, various phase transitions are observed. For x = 0.40, a susceptibility hump is seen at 30 K, suggesting the onset of static AF order. A magnetic jump, which is likely to be triggered by charge ordering, is clearly observed at Tt = 175 K in samples with x = 0.50 (= 1/2) and 0.67 (= 2/3), while only a tiny kink appears at T = 210 K in the sample with an intermediate Li composition, x = 0.60. Thus, the phase diagram of the LixCoO2 system is complex, and the electronic properties are sensitively influenced by the Li content (x).

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T. Motohashi, T. Ono, Y. Sugimoto, Y. Masubuchi, S. Kikkawa, R. Kanno, M. Karppinen, H. Yamauchi. 2009-10-17. Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0). https://doi.org/10.1103/physrevb.80.165114

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