Hybrid gap structure in the heavy-fermion superconductor CeIrIn${}_5$

Abstract

The thermal conductivity $\kappa$ of the heavy-fermion superconductor CeIrIn${}_5$ was measured as a function of temperature down to $T_c$/8, for current directions perpendicular ($J\parallel a$) and parallel ($J\parallel c$) to the tetragonal c axis. For $J\parallel a$, a sizable residual linear term ${\kappa }_0/T$ is observed, as previously, which confirms the presence of line nodes in the superconducting gap. For $J\parallel c$, on the other hand, $\kappa /T\to 0$ as $T\to 0$. The resulting precipitous decline in the anisotropy ratio ${\kappa }_c/{\kappa }_a$ at low temperature rules out a gap structure with line nodes running along the c-axis, such as the d-wave state favoured for CeCoIn${}_5$, and instead points to a hybrid gap of $E_g$ symmetry. It therefore appears that two distinct superconducting states are realized in the Ce$M$In${}_5$ family.

4 pages, 3 figures, submitted to Phys. Rev. Lett

References in corpus (1)

• Unpaired Electrons in the Heavy-Fermion Superconductor CeCoIn_{5}

Cited by in corpus (3)

• Thermal conductivity evidence for d_{x^2-y^2} pairing symmetry in the heavy-fermion CeIrIn5 superconductor
• Ambient-pressure bulk superconductivity deep in the magnetic state of CeRhIn5
• Universal heat transport in a heavy-fermion superconductor