Strontium Ruthenate (Sr2RuO4) is a strongly correlated complex oxide for which crystals with exquisite purity can be prepared, allowing for a wealth of experimental studies. It displays unconventional superconductivity, Hund's metal physics, and an incommensurate anti-ferromagnetic spin response.
To understand the interplay of collective spin excitations and the Fermi liquid quasi particles we have performed density functional theory and dynamical mean field theory calculations of the dynamic magnetic susceptibility using the Bethe-Salpeter equation, comparing to recent inelastic neutron scattering results.
The crucial importance of local quantum fluctuations in the vertex is established by comparison with the static random phase approximation. We also study the spin-orbit driven anisotropy and disentangle the orbital contributions. Our findings confirm that this material is close to a magnetic instability, as revealed by its sensitivity to impurity substitutions. Finally, by comparing the local and momentum dependent response, we pinpoint signatures of Hund's metal physics in the inelastic neutron spectra.