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TT: Fachverband Tiefe Temperaturen

TT 67: Unconventional Superconductors

TT 67.3: Vortrag

Donnerstag, 21. März 2024, 10:15–10:30, H 3007

Evidence for vertical line nodes in Sr₂RuO₄ from nonlocal electrodynamics — •Javier Landaeta^1,2, Konstantin Semeniuk², Joost Aretz², Ismardo Bonalde³, Jörg Schmalian⁴, Andrew Mackenzie², and Elena Hassinger¹ — ¹Institute of Solid State and Materials Physics, TU Dresden, 01069, Dresden, Germany — ²Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany — ³Centro de Física, Instituto Venezolano de Investigaciones Científicas, Caracas 1020-A, Venezuela — ⁴Institute for Theoretical Condensed Matter Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

By determining the superconducting lower and upper critical fields H_c1(T) and H_c2(T), respectively, in a high-purity spherical Sr₂RuO₄ sample via ac-susceptibility measurements, we obtain the temperature dependence of the coherence length ξ and the penetration depth λ down to 0.04 T_c. Given the high sample quality, the observed T² dependence of λ at low temperatures cannot be explained in terms of impurity effects. Instead, we argue that the weak type-II superconductor Sr₂RuO₄ has to be treated in the non-local limit. In that limit, the penetration depth data agree with a gap structure having vertical line nodes of the superconducting gap, while horizontal line nodes cannot account for the observation.