2010/07/28 by Hiroto Ohta, Chishiro Michioka, Ohta, Hiroto +5
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Solid-state spectroscopy and crystallography #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.1007.4873
4 pages, 5 figures, submitted to PRL on November 2nd 2007, revised on July 28 2010
arxiv created 2010/07/28 · openalex publication_date 2010/07/28 · arxiv updated 2010/07/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report duration dependence of superconductivity in a 43 % humidity atmosphere and 59Co nuclear quadrupole resonance (NQR) of polycrystalline samples of bilayer hydrated NaxCoO2 ⋅ yH2O. We found a reentrant behavior of superconductivity with respect to the time duration. We obtained the universal phase diagram where two superconducting phases and an in-between magnetic phase are classified by 59Co NQR frequency. Zero field 59Co nuclear spin-lattice relaxation rates 1/T1 indicated a magnetic critical slowing down at 5 K in the magnetic phase, excluding a charge density wave ordering, and an enhancement at and just above Tc in a new superconducting phase, suggesting a coexistence of magnetic ordering.