Possible singlet to triplet pairing transition in NaxCoO2 H2O

Abstract

We present precise measurements of the upper critical field (Hc2) in the recently discovered cobalt oxide superconductor. We have found that the critical field has an unusual temperature dependence; namely, there is an abrupt change of the slope of Hc2(T) in a weak field regime. In order to explain this result we have derived and solved Gor'kov equations on a triangular lattice. Our experimental results may be interpreted in terms of the field-induced transition from singlet to triplet superconductivity.

arXiv comment6 pages, 5 figures, revtex

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Cited by in corpus (11)

• Evidence of nodal superconductivity in Na_0.35CoO2-1.3H_2O: a specific heat study
• Valence and Na content dependences of superconductivity in NaxCoO2.yH2O
• Superconductivity in the presence of disorder in skutterudite-related La${}_3$Co${}_4$Sn${}_{13}$ and La${}_3$Ru${}_4$Sn${}_{13}$ compounds; electrical transport and magnetic studies
• Holes and magnetic polarons in a triangular lattice antiferromagnet
• Superconductivity in a layered cobalt oxychalcogenide Na${}_2$CoSe${}_2$O with a triangular lattice
• Pairing state in multicomponent superconductors
• Superconducting phase diagram of NaxCoO2.yH2O
• Numerical study of magnetic and pairing correlation in bilayer triangular lattice
• Upper critical field of aligned Na_{x}(H_{3}O)_{z}CoO_{2}\cdot yH_{2}O superconductor by magnetization measurement
• Thermodynamic properties in triangular-lattice superconductors
• Anomalous behaviour of the temperature dependencies of the upper critical fields in (Dy1-xErx)Rh3.8Ru0.2B4 (x=0, 0.2, 0.4)