Department of Materials Engineering Science, Osaka University, Osaka 560-8531, Japan.
Phys Rev Lett. 2012 Sep 14;109(11):117001. doi: 10.1103/PhysRevLett.109.117001.
We report on a pressure-induced evolution of exotic superconductivity and spin correlations in CeIr(In(1-x)Cd(x))(5) by means of in-nuclear-quadrupole-resonance (NQR) studies. Measurements of an NQR spectrum and nuclear-spin-lattice-relaxation rate 1/T(1) have revealed that antiferromagnetism induced by Cd doping emerges locally around Cd dopants, but superconductivity is suddenly induced at T(c)=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 which increases with T(c) 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(In(1-x)Cd(x))(5) system may be mediated by valence fluctuations.
我们通过核四极共振（NQR）研究报告了 CeIr(In(1-x)Cd(x))(5)中由压力诱导的奇特超导性和自旋关联的演变。NQR 光谱和核自旋晶格弛豫率 1/T(1)的测量表明，Cd 掺杂引起的反铁磁性局部出现在 Cd 掺杂剂周围，但超导性分别在 2.34 和 2.75 GPa 时在 T(c)=0.7 和 0.9 K 突然出现。具有在费米能级处剩余态密度分数随 T(c)增加的独特超导特性与由反铁磁关联介导的各向异性超导性不同。通过结合 NQR 频率对 Ce 价态变化的压力依赖性，我们提出 CeIr(In(1-x)Cd(x))(5)体系中的非常规超导性可能由价态波动介导。
