observed by polarized neutron scattering*

The superconducting state of Sr₂RuO₄ was considered to inhere chiral-triplet pairing analogue to the superfluid ³He-A phase [1]. This has recently been challenged by observations of a reduced ¹⁷O-NMR Knight shift in the superconducting state [2]. Here we present a new measurement of the spin susceptibility by polarized neutron scattering. The results show consistent with NMR [2] a suppression below the superconducting transition and reject the previously accepted picture. Differences to a previous polarized neutron scattering study at higher magnetic field [3] are understood by a complex field dependence and lesser statistics. Quantitatively, these results are consistent with different gap states than NMR [2] but support recent proposals such as nodal s’+id or d+ig [4].
[1] Maeno et al., Nature 372, 532 (1994); Rice et al., J. Phys.: Condens. Matter 7, L643 (1995)
[2] Pustogow et al., Nature 574, 72 (2019); Ishida et al., J. Phys. Soc. Jpn. 89, 034712 (2020); Chronister et al., arXiv:2007.13730 (2020)
[3] Duffy et al., Phys. Rev. Lett. 85, 5412 (2000)
[4] Rømer et al., Phys. Rev. Lett. 123, 247001 (2019)