Evidence for eight node mixed-symmetry superconductivity in a correlated organic metal

Daniel Guterding; Sandra Diehl; Michaela Altmeyer; Torsten Methfessel; Ulrich Tutsch; Harald Schubert; Michael Lang; Jens Müller; Michael Huth; Harald O. Jeschke; Roser Valenti; Martin Jourdan; Hans-Joachim Elmers

doi:10.1103/physrevlett.116.237001

arXiv · 1510.09209

Evidence for eight node mixed-symmetry superconductivity in a correlated organic metal

Daniel Guterding·Sandra Diehl·Michaela Altmeyer·Torsten Methfessel·Ulrich Tutsch·Harald Schubert·Michael Lang·Jens Müller·Michael Huth·Harald O. Jeschke·Roser Valenti·Martin Jourdan·Hans-Joachim Elmers

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Abstract

We report a combined theoretical and experimental investigation of the superconducting state in the quasi-two-dimensional organic superconductor $\kappa$-(ET)$_2$Cu[N(CN)$_2$]Br. Applying spin-fluctuation theory to a low-energy material-specific Hamiltonian derived from ab initio density functional theory we calculate the quasiparticle density of states in the superconducting state. We find a distinct three-peak structure that results from a strongly anisotropic mixed-symmetry superconducting gap with eight nodes and twofold rotational symmetry. This theoretical prediction is supported by low-temperature scanning tunneling spectroscopy on in situ cleaved single crystals of $\kappa$-(ET)$_2$Cu[N(CN)$_2$]Br with the tunneling direction parallel to the layered structure.

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Daniel Guterding, Sandra Diehl, Michaela Altmeyer, Torsten Methfessel, Ulrich Tutsch, Harald Schubert, Michael Lang, Jens Müller, Michael Huth, Harald O. Jeschke, Roser Valenti, Martin Jourdan, Hans-Joachim Elmers. 2015-10-30. Evidence for eight node mixed-symmetry superconductivity in a correlated organic metal. https://doi.org/10.1103/physrevlett.116.237001

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