Muon Knight shift as a precise probe of the superconducting symmetry of Sr${}_2$RuO${}_4$

Abstract

Muon spin rotation ($\mu$SR) measurements of internal magnetic field shifts, known as the muon Knight shift, is used for determining pairing symmetries in superconductors. While this technique has been especially effective for $f$-electron-based heavy-fermion superconductors, it remains challenging in $d$-electron-based superconductors such as Sr${}_2$RuO${}_4$, where the Knight shift is intrinsically small. Here, we report high-precision muon Knight shift measurements of superconducting Sr${}_2$RuO${}_4$. We observe that using multiple pieces of crystals, a common practice in $\mu$SR measurements, induces a substantial paramagnetic shift below the superconducting transition temperature, $T_c$, when a weak magnetic field is applied. We attribute such an unresolved paramagnetic shift to stray fields generated by neighboring diamagnetic crystals. To avoid this, one piece of crystal was used in this study. We experimentally determine the muon Knight shift of Sr${}_2$RuO${}_4$ in the normal state to be -116$\pm$7 ppm. By combining the observed muon Knight shift with independently determined bulk magnetization data from the same crystal used in $\mu$SR and carefully separating various contributions to the shift, we confirm a significant reduction in the spin Knight shift below $T_c$, consistent with spin-singlet-like pairing. This result constitutes the precise muon Knight shift measurement in a $d$-electron-based superconductor. Our results highlight the potential of $\mu$SR as a powerful complementary technique to the established method of nuclear magnetic resonance for probing the spin susceptibility in superconductors.

References in corpus (32)

• Time-Reversal Symmetry Breaking Superconductivity in Sr2RuO4
• High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State
• Fulde-Ferrell-Larkin-Ovchinnikov State in Heavy Fermion Superconductors
• Pronounced drop of ${}^{17}$O NMR Knight shift in superconducting state of Sr${}_2$RuO${}_4$
• Observation of half-height magnetization steps in Sr2RuO4
• Gap Structure of the Spin-Triplet Superconductor Sr2RuO4 Determined from the Field-Orientation Dependence of Specific Heat
• Split superconducting and time-reversal symmetry-breaking transitions, and magnetic order in Sr${}_2$RuO${}_4$ under uniaxial stress
• Reduction of the ${}^{17}$O Knight shift in the Superconducting State and the Heat-up Effect by NMR Pulses on Sr${}_2$RuO${}_4$
• Recent progress on superconductors with time-reversal symmetry breaking
• Stabilizing Even-Parity Chiral Superconductivity in Sr${}_2$RuO${}_4$
• Modified Sagnac interferometer for high-sensitivity magneto-optic measurements atcryogenic temperatures
• Evidence for even parity unconventional superconductivity in Sr${}_2$RuO${}_4$
• Comparison of different methods for analyzing $\mu$SR line shapes in the vortex state of type-II superconductors
• Reduction of the spin susceptibility in the superconducting state of Sr2RuO4 observed by polarized neutron scattering
• Unsplit superconducting and time reversal symmetry breaking transitions in Sr${}_2$RuO${}_4$ under hydrostatic pressure and disorder
• Searching for gap zeros in Sr2RuO4 via field-angle-dependent specific-heat measurement
• Angular dependence of the upper critical field of Sr2RuO4
• Sharp magnetization jump at the first-order superconducting transition in Sr2RuO4
• Improved Single-Crystal Growth of Sr${}_2$RuO${}_4$
• Muon-spin rotation measurements of the vortex state in Sr${}_2$RuO${}_4$: type-1.5 superconductivity, vortex clustering and a crossover from a triangular to a square vortex lattice
• Unveiling unconventional magnetism at the surface of Sr${}_2$RuO${}_4$
• DFT+μ: Density Functional Theory for Muon Site Determination
• Superconductivity and Field-Induced Magnetism in Pr${}_{2-x}$Ce${}_x$CuO${}_4$ Single Crystals
• Spin moiré engineering of topological magnetism and emergent electromagnetic fields
• Pauli-paramagnetic effects on mixed state properties in a strongly anisotropic superconductor ---Application to Sr_2_RuO_4_---
• Intrinsic nature of spontaneous magnetic fields in superconductors with time-reversal symmetry breaking
• Compact AC Susceptometer for Fast Sample Characterization down to 0.1 K
• Time-reversal invariant and fully gapped unconventional superconducting state in the bulk of the topological Nb0.25Bi2Se3
• In-plane magnetic penetration depth in Sr${}_2$RuO${}_4$: muon-spin rotation/relaxation study
• $\mu$SR measurements on Sr${}_2$RuO${}_4$ under $⟨110⟩$ uniaxial stress
• ${\mu }^{+}$ Knight Shift in UTe${}_2$: Evidence for Relocalization in a Kondo Lattice
• Penetration depth and gap structure in the antiperovskite oxide superconductor Sr${}_{3-x}$SnO revealed by $\mu$SR

Cited by in corpus (1)

• Ultrasonic Observation of Slowing Down of Multipole Fluctuations in Sr${}_2$RuO${}_4$