Inelastic neutron scattering experiments on ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ determine the spectral weight of the nesting induced magnetic fluctuations across the superconducting transition. There is no observable change at the superconducting transition down to an energy of $\sim 0.35\mathrm{meV}$, which is well below the $2\mathrm{\Delta }$ values reported in several tunneling experiments. At this and higher energies magnetic fluctuations clearly persist in the superconducting state. Only at energies below $\sim 0.3\mathrm{meV}$ can evidence for partial suppression of spectral weight in the superconducting state be observed. This strongly suggests that the one-dimensional bands with the associated nesting fluctuations do not form the active, highly gapped bands in the superconducting pairing in ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$.

• Received 16 June 2016

DOI:https://doi.org/10.1103/PhysRevLett.118.147002