Abstract
Recent observations [A. Pustogow et al., Nature (London) 574, 72 (2019).] of a drop of the nuclear magnetic resonance (NMR) Knight shift in the superconducting state of challenged the popular picture of a chiral odd-parity paired state in this compound. Here we use polarized neutron scattering (PNS) to show that there is a drop in the magnetic susceptibility at the Ru site below the superconducting transition temperature. We measure at lower fields than a previous PNS study allowing the suppression to be observed. The PNS measurements show a smaller susceptibility suppression than NMR measurements performed at similar field and temperature. Our results rule out the chiral odd-parity state and are consistent with several recent proposals for the order parameter including even-parity and odd-parity helical states.
- Received 7 February 2020
- Revised 1 July 2020
- Accepted 14 October 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.217004
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