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Free keywords:
Charged particles, Electronic structure, Energy gap, Ruthenium compounds, Spin dynamics, Strontium compounds, % reductions, Gap functions, Linear temperature dependence, Magnetic penetration depth, Measurements of, Muon spin rotation, Muon spin rotation and relaxation, Relaxation studies, Rotation relaxation, Superconducting gaps, Temperature distribution
Abstract:
We report on measurements of the in-plane magnetic penetration depth (λab) in single crystals of Sr2RuO4 down to ≃0.015 K by means of muon-spin rotation-relaxation. The linear temperature dependence of λab-2 for T≲0.7 K suggests the presence of nodes in the superconducting gap. This statement is further substantiated by observation of the Volovik effect, i.e., the reduction of λab-2 as a function of the applied magnetic field. The experimental zero-field and zero-temperature value of λab=124(3) nm agrees with λab≃130 nm, calculated based on results of electronic structure measurements reported in A. Tamai et al. [High-resolution photoemission on Sr2RuO4 reveals correlation-enhanced effective spin-orbit coupling and dominantly local self-energies, Phys. Rev. X 9, 021048 (2019)PRXHAE2160-330810.1103/PhysRevX.9.021048]. Our analysis reveals that a simple nodal superconducting energy gap, described by the lowest possible harmonic of a gap function, does not capture the dependence of λab-2 on T, so the higher angular harmonics of the energy gap function need to be introduced. © 2023 American Physical Society.
