Possible spin triplet superconductivity in NaxCoO2·yH2O —59Co NMR studies

2003/06/30 by M. Kato, Masaki Kato, Chishiro Michioka +16
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Atomic physics #Chemistry #Condensed matter physics #Hyperfine structure #Knight shift #Magnetic and transport properties of perovskites and related materials #Magnetic susceptibility #NMR spectra database #Nuclear quadrupole resonance #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Spectral line #Spin–lattice relaxation #Superconductivity #cond-mat.str-el #cond-mat.supr-con

paper · pdf · doi:10.1088/0953-8984/18/2/022

published as J. Phys.: Condens. Matter 18 (2006) 669-682 · 17 pages, 10 figures. Extended version

arxiv created 2005/07/01 · openalex publication_date 2005/12/14 · arxiv updated 2015/06/24 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We report 59Co NMR studies on the magnetically oriented powder samples of Co-oxide superconductors NaxCoO2yH2O with Tc ~ 4.7 K. From two-dimensional powder pattern in the NMR spectrum, the ab-plane Knight shift in the normal state was estimated by the magnetic field dependence of second-order quadrupole shifts at various temperatures. Below 50 K, the Knight shift shows a Curie-Weiss-like temperature dependence, similarly to the bulk magnetic susceptibility chi. From the analysis of so-called K-chi plot, the spin and the orbital components of K and the positive hyperfine coupling constant were estimated. The onset temperature of superconducting transition in the Knight shift does not change so much in an applied magnetic field up to 7 T, which is consistent with the reported high upper critical field Hc2. The Knight shift at 7 T shows an invariant behavior below Tc. No coherence peak just below Tc was observed in the temperature dependence of the nuclear spin-lattice relaxation rate 1/T1 in both cases of NMR and NQR. We conclude that the invariant behavior of the Knight shift below Tc and unconventional behaviors of 1/T possibly indicate the spin-triplet superconductivity with p- or f-wave symmetry.

Citations

• Possible Spin-Tripletf-Wave Pairing Due to Disconnected Fermi Surfaces In NaxCoO2·yH2O
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