Spin susceptibility for orbital-singlet Cooper pair in the three-dimensional Sr2RuO4 superconductor

We study the spin susceptibility of the orbital-singlet pairings, including the spin-triplet/orbital-singlet/s-wave E-g representation proposed by Suh et al. [H. G. Suh et al., Phys. Rev. Research 2, 032023(R) (2020)], for a three orbital model of superconducting Sr2RuO4 in three dimensions. For the pseudospin-singlet states represented in the band basis, the spin susceptibility decreases when reducing the temperature, irrespective of the direction of the applied magnetic fields, even if they are spin-triplet/orbital-singlet pairings in the spin-orbital space. However, because the pseudospin-triplet d-vector in the band basis is not completely aligned in the xy-plane (along z-axis) owing to the strong atomic spin-orbit coupling, the spin susceptibility for spin-singlet/orbital-singlet/odd-parity pairings is reduced around 5???10 percent with the decrease of the temperature along the z (x) axis. We can determine the symmetry of the pseudospin structure of the Cooper pair by the temperature dependence of the spin susceptibility measured by nuclear magnetic resonance experiments. Our obtained results serve as a guide to determine the pairing symmetry of Sr2RuO4.

Automated summary

We investigated the spin susceptibility of orbital-singlet pairings in a three-dimensional three-orbital model of superconducting Sr2RuO4. The spin susceptibility decreases with decreasing temperature, regardless of the direction of the applied magnetic fields. However, the spin susceptibility for certain pairings is reduced by around 5-10% along the z (x) axis due to the alignment of the pseudospin-triplet d-vector in the band basis. The temperature dependence of the spin susceptibility measured by nuclear magnetic resonance experiments can be used to determine the symmetry of the pseudospin structure of the Cooper pair, providing guidance for determining the pairing symmetry of Sr2RuO4.