Symmetry change of $d$-wave superconductivity in $\kappa$-type organic superconductors

Abstract

Magnetic-field-angle-resolved heat capacity of dimer-Mott organic superconductors $\kappa$-(BEDT-TTF)${}_2$$X$ is reported. Temperature and field dependence of heat capacity indicates that the superconductivity has line nodes on the Fermi surface, which is a typical feature of $d$-wave superconductivity. In-plane field-angle dependence exhibits fourfold oscillations as well as twofold oscillations due to anisotropy of superconducting gap functions. From analyses of the fourfold term, the gap symmetry is determined as $d_{x^2-y^2}$+$s_{\pm }$ for $X$=Cu[N(CN)${}_2$]Br and $d_{xy}$ for $X$=Ag(CN)${}_2$H${}_2$O. We suggest that the symmetry difference comes from the competition of $d_{xy}$ and $d_{x^2-y^2}$ antiferromagnetic fluctuations depending on lattice geometry.

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References in corpus (5)

• Specific heat measurements of the gap structure of the organic superconductors kappa-(ET)_2Cu[N(CN)_2]Br and kappa-(ET)_2Cu(NCS)_2
• Superconductivity and a Mott Transition in a Hubbard Model on an Anisotropic Triangular Lattice
• Unconventional superconductors under rotating magnetic field I: density of states and specific heat
• Vortex State and Field-Angle Resolved Specific Heat Oscillation for H // ab in d-Wave Superconductors
• Phase Competition and Superconductivity in $\kappa$-(BEDT-TTF)${}_2$X: Importance of Intermolecular Coulomb Interactions

Cited by in corpus (5)

• Thermodynamic evidence for the formation of a Fulde-Ferrell-Larkin-Ovchinnikov phase in the organic superconductor $\lambda$-(BETS)${}_2$GaCl${}_4$
• Superconductivity and Mottness in Organic Charge Transfer Materials
• Pseudogap formation in organic superconductors
• Thermodynamic Properties of the Mott Insulator-Metal Transition in a Triangular Lattice System Without Magnetic Order
• Persistence of fermionic spin excitations through a genuine Mott transition in $\kappa$-type organics