We report the in-plane resistivity and magnetic susceptibility of the layered cobalt oxide Na0.35CoO2·1.3H2O single crystal. The temperature dependence of the resistivity shows metallic behavior from room temperature to the superconducting transition temperature Tc of 4.5 K. A sharp resistive transition, zero resistivity and almost perfect superconducting volume fraction below Tc indicate the good quality and bulk superconductivity of the single crystal. The upper critical field Hc2 and coherence length ξ are obtained from the resistive transitions in the magnetic fields parallel to the c-axis and ab-plane. The anisotropy of ξ, ξab/ξc = 12 nm/1.3 nm ≃ 9.2, suggests that this material is an anisotropic three-dimensional superconductor. In the field parallel to the ab-plane, Hc2 seems to be suppressed to the Pauli paramagnetic limit. This suggests spin singlet superconductivity in the cobalt oxide.
ASJC Scopus subject areas
- Physics and Astronomy(all)