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

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.

Accepted for publication in Phys. Rev. Lett.;6+12 pages;3+13 figures

References in corpus (16)

• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Strong electronic correlations in superconducting organic charge transfer salts
• A review of two-band superconductivity: materials and effects on the thermodynamic and reversible mixed-state properties
• Specific heat measurements of the gap structure of the organic superconductors kappa-(ET)_2Cu[N(CN)_2]Br and kappa-(ET)_2Cu(NCS)_2
• Ab initio two-dimensional multiband low-energy models of EtMe_3Sb[Pd(dmit)_2]_2 and κ-(BEDT-TTF)_2Cu(NCS)_2 with comparisons to single-band models
• Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe
• Symmetry of the superconducting order parameter in frustrated systems determined by the spatial anisotropy of spin correlations
• Single-particle excitations under coexisting electron correlation and disorder: a numerical study of the Anderson-Hubbard model
• Influence of molecular conformations on the electronic structure of organic charge transfer salts
• Bogoliubov angle and visualization of particle-hole mixture in superconductors
• Mott metal-insulator transition induced by utilizing a glass-like structural ordering in low-dimensional molecular conductors
• Origin of the superconducting state in the collapsed tetragonal phase of KFe2As2
• Origin of the glass-like dynamics in molecular metals $\kappa$-(BEDT-TTF)${}_{\text{2}}$X: implications from fluctuation spectroscopy and $\text{ab initio}$ calculations
• Superconductor-Insulator Phase Separation Induced by Rapid Cooling in kappa-(ET)_2Cu[N(CN)_2]Br
• Antiferromagnetic Spin Fluctuations in the Metallic Phase of Quasi-Two-Dimensional Organic Superconductors
• Role of layer packing for the electronic properties of the organic superconductor (BEDT-TTF)${}_2$Ag(CF${}_3$)${}_4$(TCE)

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