1,078 research outputs found
Nuclear Magnetic Relaxation Rate in Iron-Pnictide Superconductors
Nuclear magnetic relaxation rate 1/T_1 in iron-pnictide superconductors is
calculated using the gap function obtained in a microscopic calculation. Based
on the obtained results, we discuss the issues such as the rapid decrease of
1/T_1 just below the transition temperature and the difference between nodeless
and nodal s-wave gap functions. We also investigate the effect of Coulomb
interaction on 1/T_1 in the random phase approximation and show its importance
in interpreting the experimental results.Comment: Proceedings of 9th International Conference on Materials and
Mechanisms of Superconductivity. To be published in Physica
Enhancement of Superconducting Transition Temperature due to the strong Antiferromagnetic Spin Fluctuations in Non-centrosymmetric Heavy-fermion Superconductor CeIrSi3 :A 29Si-NMR Study under Pressure
We report a 29Si-NMR study on the pressure-induced superconductivity (SC) in
an antiferromagnetic (AFM) heavy-fermion compound CeIrSi3 without inversion
symmetry. In the SC state at P=2.7-2.8 GPa, the temperature dependence of the
nuclear-spin lattice relaxation rate 1/T_1 below Tc exhibits a T^3 behavior
without any coherence peak just below Tc, revealing the presence of line nodes
in the SC gap. In the normal state, 1/T_1 follows a \sqrt{T}-like behavior,
suggesting that the SC emerges under the non-Fermi liquid state dominated by
AFM spin fluctuations enhanced around quantum critical point (QCP). The reason
why the maximum Tc in CeIrSi3 is relatively high among the Ce-based
heavy-fermion superconductors may be the existence of the strong AFM spin
fluctuations. We discuss the comparison with the other Ce-based heavy-fermion
superconductors.Comment: 4 pages, 5 figures, To be published in Phys. Rev. Let
Spin Susceptibility of Noncentrosymmetric Heavy-fermion Superconductor CeIrSi3 under Pressure: 29Si-Knight Shift Study on Single Crystal
We report 29Si-NMR study on a single crystal of the heavy-fermion
superconductor CeIrSi3 without an inversion symmetry along the c-axis. The
29Si-Knight shift measurements under pressure have revealed that the spin
susceptibility for the ab-plane decreases slightly below Tc, whereas along the
c-axis it does not change at all. The result can be accounted for by the spin
susceptibility in the superconducting state being dominated by the strong
antisymmetric (Rashba-type) spin-orbit interaction that originates from the
absence of an inversion center along the c-axis and it being much larger than
superconducting condensation energy. This is the first observation which
exhibits an anisotropy of the spin susceptibility below Tc in the
noncentrosymmetric superconductor dominated by strong Rashba-type spin-orbit
interaction.Comment: 4 pages, 4 figures, Accepted for publication in Phys. Rev. Let
Possibility of valence-fluctuation mediated superconductivity in Cd-doped CeIrIn probed by In-NQR
We report on a pressure-induced evolution of exotic superconductivity and
spin correlations in CeIr(InCd) by means of
In-Nuclear-Quadrupole-Resonance (NQR) studies. Measurements of an NQR spectrum
and nuclear-spin-lattice-relaxation rate have revealed that
antiferromagnetism induced by the Cd-doping emerges locally around Cd dopants,
but superconductivity is suddenly induced at = 0.7 and 0.9 K at 2.34 and
2.75 GPa, respectively. The unique superconducting characteristics with a large
fraction of the residual density of state at the Fermi level that increases
with differ from those for anisotropic superconductivity mediated by
antiferromagnetic correlations. By incorporating the pressure dependence of the
NQR frequency pointing to the valence change of Ce, we suggest that
unconventional superconductivity in the CeIr(InCd) system may
be mediated by valence fluctuations.Comment: Accepted for publication in Physical Review Letter
Preparation and characterization of Mo/Y-zeolite and its catalytic activity for propene metathesis
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