paper

Fully gapped $d$ -wave superconductivity in CeCu $_{2}$ Si $_{2}$

arXiv:1605.04786 · doi:10.1073/pnas.1720291115

Abstract

The nature of the pairing symmetry of the first heavy fermion superconductor CeCu $_{2}$ Si $_{2}$ has recently become the subject of controversy. While CeCu $_{2}$ Si $_{2}$ was generally believed to be a $d$ -wave superconductor, recent low temperature specific heat measurements showed evidence for fully gapped superconductivity, contrary to the nodal behavior inferred from earlier results. Here we report London penetration depth measurements, which also reveal fully gapped behavior at very low temperatures. To explain these seemingly conflicting results, we propose a fully gapped $d + d$ band-mixing pairing state for CeCu $_{2}$ Si $_{2}$ , which yields very good fits to both the superfluid density and specific heat, as well as accounting for a sign change of the superconducting order parameter, as previously concluded from inelastic neutron scattering results.

9 pages, 6 figures including Supplemental material. Published version in PNAS available online ahead of print at http://www.pnas.org/content/early/2018/05/07/1720291115

Fully gapped d-wave superconductivity in CeCu2​Si2​

Abstract

Fully gapped $d$ -wave superconductivity in CeCu $_{2}$ Si $_{2}$