Vertical line nodes in the superconducting gap structure of Sr2RuO4

Abstract

There is strong experimental evidence that the superconductor Sr2RuO4 has a chiral p-wave order parameter. This symmetry does not require that the associated gap has nodes, yet specific heat, ultrasound and thermal conductivity measurements indicate the presence of nodes in the superconducting gap structure of Sr2RuO4. Theoretical scenarios have been proposed to account for the existence of accidental nodes or deep accidental minima within a p-wave state. To elucidate the nodal structure of the gap, it is essential to know whether the lines of nodes (or minima) are vertical (parallel to the tetragonal c axis) or horizontal (perpendicular to the c axis). Here, we report thermal conductivity measurements on single crystals of Sr2RuO4 down to 50 mK for currents parallel and perpendicular to the c axis. We find that there is substantial quasiparticle transport in the T = 0 limit for both current directions. A magnetic field H immediately excites quasiparticles with velocities both in the basal plane and in the c direction. Our data down to Tc/30 and down to Hc/100 show no evidence that the nodes are in fact deep minima. Relative to the normal state, the thermal conductivity of the superconducting state is found to be very similar for the two current directions, from H = 0 to H = Hc2. These findings show that the gap structure of Sr2RuO4 consists of vertical line nodes. Given that the c-axis dispersion (warping) of the Fermi surface in Sr2RuO4 varies strongly from surface to surface, the small a-c anisotropy suggests that the line nodes are present on all three sheets of the Fermi surface. If imposed by symmetry, vertical line nodes would be inconsistent with a p-wave order parameter for Sr2RuO4. To reconcile the gap structure revealed by our data with a p-wave state, a mechanism must be found that produces accidental line nodes in Sr2RuO4.

arXiv commentaccepted for publication in PRX, an extra figure has been added to compare the effect of impurity scattering on p-wave vs d-wave states

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Cited by in corpus (69)

• Stabilizing Even-Parity Chiral Superconductivity in Sr${}_2$RuO${}_4$
• Knight Shift and Leading Superconducting Instability From Spin Fluctuations in Sr2RuO4
• Superconducting order parameter of Sr${}_2$RuO${}_4$: a microscopic perspective
• Reduction of the spin susceptibility in the superconducting state of Sr2RuO4 observed by polarized neutron scattering
• Orientation-dependent Josephson effect in spin-singlet superconductor/altermagnet/spin-triplet superconductor junctions
• Searching for gap zeros in Sr2RuO4 via field-angle-dependent specific-heat measurement
• Superconducting Symmetries of Sr${}_2$RuO${}_4$ from First-Principles Electronic Structure
• Inhomogeneous time-reversal symmetry breaking in ${\mathrm{Sr}}_2\mathrm{Ru}{\mathrm{O}}_4$
• Superconducting state of Sr${}_2$RuO${}_4$ in the presence of longer-range Coulomb interactions
• Superconducting order of ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ from a three-dimensional microscopic model
• Time-Reversal Invariant Superconductivity of Sr${}_2$RuO${}_4$ Revealed by Josephson Effects
• Symmetry indicators for topological superconductors
• Theory of chiral $p$-wave superconductivity with near-nodes for Sr${}_2$RuO${}_4$
• Little-Parks oscillations with half-quantum fluxoid features in Sr2RuO4 micro rings
• Theory of Strain-Induced Magnetic Order and Splitting of $T_c$ and $T_{\mathrm{TRSB}}$ in Sr${}_2$RuO${}_4$
• Group-theoretic classification of superconducting states of Strontium Ruthenate
• Possible three-dimensional nematic odd-parity superconductivity in Sr${}_2$RuO${}_4$
• Shadowed triplet pairings in Hund's metals with spin-orbit coupling
• Exotic Cooper pairing in multi-orbital models of Sr${}_2$RuO${}_4$
• Superconducting pairing in Sr${}_2$RuO${}_4$ from weak to intermediate coupling
• Higher angular momentum pairings in interorbital shadowed-triplet superconductors: Application to Sr${}_2$RuO${}_4$
• Heat capacity double transitions in time-reversal symmetry broken superconductors
• Symmetry-based approach to nodal structures: Unification of compatibility relations and gapless point classifications
• Normal state ${}^{17}$O NMR studies of Sr${}_2$RuO${}_4$ under uniaxial stress
• Inter-orbital singlet pairing in Sr${}_2$RuO${}_4$: a Hund's superconductor
• Superconductivity in Correlated Multi-Orbital Systems with Spin-Orbit Coupling: Coexistence of Even- and Odd-Frequency Pairing and the Case of Strontium Ruthenate
• Multi-component order parameter superconductivity of Sr${}_2$RuO${}_4$ revealed by topological junctions
• Horizontal Line Nodes in Sr2RuO4 Proved by Spin Resonance
• Leading superconducting instabilities in three-dimensional models for Sr2RuO4
• Spin gap and L modulated intensity at the low-energy incommensurate magnetic fluctuations in the superconducting state of Sr2RuO4
• Superconductivity in Sr${}_2$RuO${}_4$ thin film under biaxial strain
• Constraints on the superconducting state of Sr${}_2$RuO${}_4$ from elastocaloric measurements
• In-plane magnetic penetration depth in Sr${}_2$RuO${}_4$: muon-spin rotation/relaxation study
• Simultaneous Evidence for Pauli Paramagnetic Effects and Multiband Superconductivity in KFe${}_2$As${}_2$ by Small-Angle Neutron Scattering Studies of the Vortex Lattice
• Anisotropy and multiband superconductivity in Sr2RuO4
• Pair-Density-Wave Order and Paired Fractional Quantum Hall Fluids
• Multiband mean-field theory of the $d+ig$ superconductivity scenario in Sr${}_2$RuO${}_4$
• Topological superconductor in quasi-one-dimensional Tl2-xMo6Se6
• Identifying possible pairing states in Sr${}_2$RuO${}_4$ by tunneling spectroscopy
• A microscopic Ginzburg--Landau theory and singlet ordering in Sr${}_2$RuO${}_4$
• Higher angular momentum pairing states in Sr${}_2$RuO${}_4$ in the presence of longer-range interactions
• Strong Increase in Ultrasound Attenuation Below T${}_{\mathrm{c}}$ in Sr${}_2$RuO${}_4$: Possible Evidence for Domains
• Multipole-fluctuation pairing mechanism of $d_{x^2-y^2}+ig$ superconductivity in Sr${}_2$RuO${}_4$
• Inter-orbital p- and d-wave pairings between $d_{xz/yz}$ and $d_{xy}$ orbitals in Sr${}_2$RuO${}_4$
• Possibility of mixed helical p-wave pairings in Sr${}_2$RuO${}_4$
• Sr${}_2$RuO${}_4$, like doped cuprates and barium bismuthate, is a negative charge-transfer gap even parity superconductor with $\frac{3}{4}$-filled oxygen band
• Suppressed fluctuations as the origin of the static magnetic order in strained Sr${}_2$RuO${}_4$
• Quantum-geometry-induced anomalous Hall effect in nonunitary superconductors and application to Sr${}_2$RuO${}_4$
• Observation of superconducting gap spectra of long-range proximity effect in Au/SrTiO${}_3$/SrRuO${}_3$/Sr${}_2$RuO${}_4$ tunnel junctions
• Degeneracy between even- and odd-parity superconductivity in the quasi-1D Hubbard model and implications for Sr2RuO4
• A review of some new perspectives on the theory of superconducting Sr${}_2$RuO${}_4$
• Effects of deep superconducting gap minima and disorder on residual thermal transport in $\mathrm{S}{\mathrm{r}}_2\mathrm{Ru}{\mathrm{O}}_4$
• Possible two-component spin-singlet pairings in Sr2RuO4
• Impurity induced double transitions for accidentally degenerate unconventional pairing states
• Effects of orbital selective dynamical correlation on the spin susceptibility and superconducting symmetries in Sr${}_2$RuO${}_4$
• Characterization of Sr2RuO4 Josephson junctions made of epitaxial films
• Electronic thermal resistivity and quasi-particle collision cross-section in semi-metals
• Theoretical studies for identifying horizontal line nodes via angle-resolved density of states measurements ---Application to Sr${}_2$RuO${}_4$---
• Superconducting gap symmetry from Bogoliubov quasiparticle interference analysis on {Sr}${}_2${RuO}${}_4$
• Effect of strain inhomogeneity on a chiral p-wave superconductor
• Superconducting gap anisotropy and topological singularities due to lattice translational symmetry and their thermodynamic signatures
• Reconciling $\pi$ phase shift in Josephson junction experiments with even-parity superconductivity in Sr${}_2$RuO${}_4$
• Nonlocal electrodynamics and the penetration depth of superconducting Sr${}_2$RuO${}_4$
• Anomalous Hall Effects in Chiral Superconductors
• Strontium Ferrite Under Pressure: Potential Analogue to Strontium Ruthenate
• Frequency-Dependent Superconducting States From the Two-Time Linear Response Theory: Application To Sr${}_2$RuO${}_4$
• Examining the possibility of chiral superconductivity in Sr${}_2$RuO${}_4$ and other compounds via applied supercurrent
• A Chiral Triplet Quasi-Two-Dimensional Superconductor in a Parallel Magnetic Field
• Josephson effects in the spin-triplet superconductor/altermagnet/spin-triplet superconductor junctions: the detection of the intrinsic $\mathbf{d}$-vector