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Observation of Bulk Superconductivity in NaxCoO2.yH2O and NaxCoO2.yD2O Powder and Single Crystals

R. Jin·B. C. Sales·P. Khalifah·D. Mandrus
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Abstract

Poly- and single-crystalline Na$_x$CoO$_2$ has been successfully intercalated with H$_2$O and D$_2$O as confirmed by X-ray diffraction and thermogravimetric analysis. Resistivity, magnetic susceptibility, and specific heat measurements show bulk superconductivity with T$_c$ close to 5 K in both cases. The substitution of deuterium for hydrogen has an effect on T$_c$ of less than 0.2 K. Investigation of the resistivity anisotropy of Na$_x$CoO$_2\cdot$yH$_2$O single crystals shows: (a) almost zero resistivity below T$_c$, and (b) an abrupt upturn at $T^* \sim$ 52 K in both the $\it {ab}$ plane and the $\it {c}$ direction. The implications of our results on the possible superconducting mechanism will be discussed.

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R. Jin, B. C. Sales, P. Khalifah, D. Mandrus. 2003-06-03. Observation of Bulk Superconductivity in NaxCoO2.yH2O and NaxCoO2.yD2O Powder and Single Crystals. https://doi.org/10.1103/physrevlett.91.217001

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