Evidence of nodal superconductivity inNa0.35CoO2·1.3H2

Abstract

Comprehensive low-temperature specific heat data C(T,H) of Na

Magnetic Correlation of NaxCoO2and Successive Phase Transitions of Na0.5CoO2–NMR and Neutron Diffraction Studies–

“…22) In any case, it seems to be important for the complete understanding of the superconductivity of Na 0.3 CoO 2 ⋅yH 2 O, to construct a consistent explanation of various kinds of experimental results. [12][13][14][15][16][17][18][19][20][21][22][23] …”

“…11) Experimental studies on the superconducting pair state of Na 0.3 CoO 2 ⋅yH 2 O have also been published by many authors: The possibility of the unconventional nature of the superconductivity have been suggested by observing the T dependence of the electronic specific heat C el . [12][13][14][15][16][17][18] However, one has to be careful to extract this conclusion, because there exist various problems, for example, the possible in-homogeneity of the superconducting T c , which may arise from the change of the number of the H 2 O molecules during the experimental processes. Many other ambiguous points have been pointed out by a recent report on C el .…”

A critical assessment of the superconducting pairing symmetry in NaxCoO2·yH2O

“…The orbital angular momentum, L , of each state is labelled in the rightmost column and conformity/non-conformity with each of our three criteria is indicated by Y/N (for yes/no) in the remaining three columns. for Na x CoO 2 ·yH 2 O have measured the temperature dependence of either specific heat 23,24 or relaxation rates (nuclear magnetic resonance 5 , nuclear quadrupole resonance 25,26 and muon spin relaxation, μSR 3,27 ). In all of these works, the authors agree that the low-temperature behaviour of the DOS is not exponential, indicating the absence of a full gap.…”

Upper Critical Field for Cobalt Oxide Superconductors

“…Discussion and conclusions The change of slope of H c2 (T ) in the cobalt oxide superconductors has been reported for the first time in Ref. [14]. Such a bend in a weak field regime is visible also in magnetization [15] and resistivity measurements (see Fig.…”