Precise Control of Band Filling in NaxCoO2

Abstract

Electronic properties of the sodium cobaltate NaxCoO2 are systematically studied through a precise control of band filling. Resistivity, magnetic susceptibility and specific heat measurements are carried out on a series of high-quality polycrystalline samples prepared at 200 C with Na content in a wide range of 0.35 =< x =< 0.70. It is found that dramatic changes in electronic properties take place at a critical Na concentration x* that lies between 0.58 and 0.59, which separates a Pauli paramagnetic and a Curie-Weiss metals. It is suggested that at x* the Fermi level touches the bottom of the a1g band at the gamma point, leading to a crucial change in the density of states across x* and the emergence of a small electron pocket around the gamma point for x > x*.

arXiv comment4 pages, 5 figures, submitted to J. Phys. Soc. Jpn

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Cited by in corpus (11)

• "Pudding mold" band drives large thermopower in Na${}_x$CoO${}_2$
• Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0)
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Direct link between low temperature magnetism and high temperature sodium order in NaxCoO2
• Discontinuous Lifshitz Transition Achieved by Band-Filling Control in NaxCoO2
• Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2
• Cyclotron motion in the vicinity of a Lifshitz transition in graphite
• Enhanced Seebeck coefficient by a filling-induced Lifshitz transition in KxRhO2
• Spin fluctuations, magnetic long-range order and Fermi surface gapping in NaxCoO2
• s-wave Superconductivity due to Suhl-Kondo Mechanism in Na${}_x$CoO${}_2\cdot y$H${}_2$O: Effect of Coulomb Interaction and Trigonal Distortion
• Interplay between magnetism and sodium vacancy ordering in NaxCoO2