Emergent loop-nodal s±-wave superconductivity in CeCu2Si2: Similarities to the iron-based superconductors

Hiroaki Ikeda, Michi To Suzuki, Ryotaro Arita

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50 Citations (Scopus)


Heavy-fermion superconductors are prime candidates for novel electron-pairing states due to the spin-orbital coupled degrees of freedom and electron correlations. Superconductivity in CeCu2Si2 discovered in 1979, which is a prototype of unconventional (non-BCS) superconductors in strongly correlated electron systems, still remains unsolved. Here we provide the first report of superconductivity based on the advanced first-principles theoretical approach. We find that the promising candidate is an s±-wave state with loop-shaped nodes on the Fermi surface, different from the widely expected line-nodal d-wave state. The dominant pairing glue is magnetic but high-rank octupole fluctuations. This system shares the importance of multiorbital degrees of freedom with the iron-based superconductors. Our findings reveal not only the long-standing puzzle in this material, but also urge us to reconsider the pairing states and mechanisms in all heavy-fermion superconductors.

Original languageEnglish
Article number147003
JournalPhysical Review Letters
Issue number14
Publication statusPublished - 2015 Apr 7


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