# Magnetic response of Sr$_2$RuO$_4$: quasi-local spin fluctuations due to Hund's coupling

## TL;DR

This paper investigates the magnetic susceptibility of Sr$_2$RuO$_4$ using dynamical mean-field theory, revealing Hund's coupling driven quasi-local spin fluctuations consistent with recent neutron scattering data.

## Contribution

It demonstrates that Hund's coupling induces quasi-local spin fluctuations in Sr$_2$RuO$_4$, providing a theoretical explanation aligned with experimental observations.

## Key findings

- Identification of broad, quasi-local spin fluctuations centered around the $$ point.
- Confirmation that Hund's coupling controls these fluctuations.
- The planar xy orbital predominantly contributes to the $$ point response.

## Abstract

We study the magnetic susceptibility in the normal state of Sr$_2$RuO$_4$ using dynamical mean-field theory including dynamical vertex corrections. Besides the well known incommensurate response, our calculations yield quasi-local spin fluctuations which are broad in momentum and centered around the $\Gamma$ point, in agreement with recent inelastic neutron scattering experiments [P. Steffens, et al., Phys. Rev. Lett. 122, 047004 (2019)]. We show that these quasi-local fluctuations are controlled by the Hund's coupling and account for the dominant contribution to the momentum-integrated response. While all orbitals contribute equally to the incommensurate response, the enhanced $\Gamma$ point response originates from the planar xy orbital.