Spin singlet pairing in the superconducting state of NaxCoO2\cdot1.3H2O: evidence from a ^{59}Co Knight shift in a single crystal

Abstract

We report a ^{59}Co Knight shift measurement in a single crystal of the cobalt oxide superconductor Na_{x}CoO_2\cdot1.3H_2O (T_c=4.25 K). We find that the shift due to the spin susceptibility, K^s, is substantially large and anisotropic, with the spin shift along the a-axis K^s_a being two times that along the c-axis K^s_c. The shift decreases with decreasing temperature (T) down to T\sim100 K, then becomes a constant until superconductivity sets in. Both K^s_a and K^s_c decrease below T_c. Our results indicate unambiguously that the electron pairing in the superconducting state is in the spin singlet form.

4 pages, 5 figures

References in corpus (1)

• Na content dependence of superconductivity and the spin correlations in Na_{x}CoO_{2}\cdot 1.3H_{2}O

Cited by in corpus (19)

• Spin Triplet Superconducting State due to Broken Inversion Symmetry in Li_2Pt_3B
• Nodal Structure of Unconventional Superconductors Probed by the Angle Resolved Thermal Transport Measurements
• ${}^{75}$As NQR and NMR studies of superconductivity and electron correlations in iron arsenide Li${}_x$FeAs
• Nodal $d+id$ pairing and topological phases on the triangular lattice: unconventional superconducting state of Na${}_x$CoO${}_2\cdot y$H${}_2$O
• Na content dependence of superconductivity and the spin correlations in Na_{x}CoO_{2}\cdot 1.3H_{2}O
• Shubnikov de Haas effect in the metallic state of Na${}_{0.3}$CoO${}_2$
• Deformation of Electronic Structures Due to CoO6 Distortion and Phase Diagrams of NaxCoO2.yH2O
• Fractional vortex lattice structures in spin triplet superconductors
• CoO2-Layer-Thickness Dependence of Magnetic Properties and Possible Two Different Superconducting States in NaxCoO2.yH2O
• 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
• Hydration-induced anisotropic spin fluctuations in Na_{x}CoO_{2}\cdot1.3H_{2}O superconductor
• Multiple odd-parity superconducting phases in bilayer transition metal dichalcogenides
• The higher-order magnetic skyrmions in non-uniform magnetic fields
• Dynamical magnetic susceptibility in the lamellar cobaltate superconductor Na_xCoO_2$\cdot y$H_2O
• Pressure dependence of the superconducting transition and electron correlations in Na_xCoO_2 \cdot 1.3H_2O
• Identifying the pairing symmetry in sodium cobalt oxide by Andreev edge states
• Band structure renormalization and weak pseudogap behavior in Na_{0.33}CoO_2: Fluctuation exchange study based on a single band model
• Upper critical field of aligned Na_{x}(H_{3}O)_{z}CoO_{2}\cdot yH_{2}O superconductor by magnetization measurement
• Magnetic anomalies of hydrous cobaltate compound Na_x(H_3O)_zCoO_2 \cdot yH_2O detected by NMR and NQR measurements