We report a combined theoretical and experimental investigation of the superconducting state in the quasi-two-dimensional organic superconductor κ-(ET)2Cu[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 κ-(ET)2Cu[N(CN)2]Br with the tunneling direction parallel to the layered structure.
@article{arxiv.1510.09209,
title = {Evidence for eight node mixed-symmetry superconductivity in a correlated organic metal},
author = {Daniel Guterding and Sandra Diehl and Michaela Altmeyer and Torsten Methfessel and Ulrich Tutsch and Harald Schubert and Michael Lang and Jens Müller and Michael Huth and Harald O. Jeschke and Roser Valenti and Martin Jourdan and Hans-Joachim Elmers},
journal= {arXiv preprint arXiv:1510.09209},
year = {2016}
}
Comments
Accepted for publication in Phys. Rev. Lett.;6+12 pages;3+13 figures