Possibility of valence-fluctuation mediated superconductivity in Cd-doped CeIrIn${}_5$ probed by In-NQR

Abstract

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 the 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 that 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.

arXiv commentAccepted for publication in Physical Review Letters

References in corpus (16)

• Heavy-fermion superconductivity in CeCoIn5 at 2.3K
• A New Heavy-Fermion Superconductor CeIrIn5: Relative of the Cuprates?
• Signatures of valence fluctuations in CeCu2Si2 under high pressure
• Reversible Tuning of the Heavy Fermion Ground State in CeCoIn${}_5$
• Enhanced Valence Fluctuations Caused by f-c Coulomb Interaction in Ce-Based Heavy Electrons: Possible Origin of Pressure-Induced Enhancement of Superconducting Transition Temperature in \Ge and Related Compounds
• Interacting Antiferromagnetic Droplets in Quantum Critical CeCoIn_5
• Superconductivity emerging near quantum critical point of valence transition
• Two Superconducting Phases in CeRh_1-xIr_xIn_5
• Coexistence of antiferromagnetic order and unconventional superconductivity in heavy fermion compounds CeRh_{1-x}Ir_xIn_5: nuclear quadrupole resonance studies
• Enhancing the Superconducting Transition Temperature in the Absence of Spin Correlations in Heavy Fermion Compound CeIrIn${}_5$
• Thermal conductivity evidence for d_{x^2-y^2} pairing symmetry in the heavy-fermion CeIrIn5 superconductor
• Enhancing the Superconducting Transition Temperature due to Strong-Coupling Effect under Antiferromagnetic Spin Fluctuations in CeRh1-xIrxIn5 : 115In-NQR Study
• Strong Coupling between Antiferromagnetic and Superconducting Order Parameters in CeRhIn${}_5$ Studied by In-NQR Spectroscopy
• Magneto-transport properties governed by the antiferromagnetic fluctuations in heavy fermion superconductor CeIrIn${}_5$
• Compressibility of $CeMI{n}_5$ and $C{e}_{2}MI{n}_8$ (M = Rh, Ir and Co) Compounds
• Superconducting gap structure of CeIrIn5 from field-angle-resolved measurements of its specific heat

Cited by in corpus (5)

• Avoided Valence Transition in a Plutonium Superconductor
• CeIrIn5: Superconductivity on a Magnetic Instability
• The Dominant Role of Critical Valence Fluctuations on High $T_{\mathrm{c}}$ Superconductivity in Heavy Fermions
• Coincidence of magnetic and valence quantum critical points in CeRhIn5 under pressure
• Magnetic structure of Cd-doped CeIrIn${}_5$