Reduction of the spin susceptibility in the superconducting state of Sr2RuO4 observed by polarized neutron scattering
Abstract
Recent observations [A.~Pustogow et al. Nature 574, 72 (2019)] of a drop of the 17O nuclear magnetic resonance (NMR) Knight shift in the superconducting state of Sr2RuO4 challenged the popular picture of a chiral odd-parity paired state in this compound. Here we use polarized neutron scattering to show that there is a 34 6 % drop in the magnetic susceptibility at the ruthenium site below the superconducting transition temperature. Measurements are made at lower fields H 13 Hc2 than a previous study allowing the suppression to be observed. Our results are consistent with the recent NMR observations and rule out the chiral odd-parity d=z(kx iky) state. The observed susceptibility is consistent with several recent proposals including even-parity B1g and odd-parity helical states.