Inelastic neutron scattering study of the magnetic fluctuations in Sr$_2$RuO$_4$

TL;DR

This study used neutron scattering to analyze magnetic fluctuations in Sr$_2$RuO$_4$, revealing persistent incommensurate peaks and magnetic fluctuations consistent with a 2D Fermi liquid model, even at room temperature.

Contribution

First detailed neutron scattering analysis of magnetic fluctuations in Sr$_2$RuO$_4$ across a wide energy range and temperatures, confirming theoretical models.

Findings

Strong incommensurate peaks at Qc=(0.3,0.3) up to 80 meV

Magnetic fluctuations connect IC peaks around (π,π)

IC fluctuations persist at room temperature

Abstract

By performing time-of-flight neutron scattering measurements on a large amount of single crystals of Sr$_2$RuO$_4$, we studied detailed structure of the imaginary part of the dynamic spin susceptibility over a wide range of phase space. In the normal state at T=5 K, strong incommensurate (IC) peaks were clearly observed at around $\mathbf{Q}_\text{c}=(0.3,0.3)$ up to at least $\hbar\omega=80$ meV. In addition, our data also show strong magnetic fluctuations that exist on the ridges connecting the IC peaks around the $(\pi,\pi)$ point rather than around the $\Gamma$ point. Our results are consistent with the semi-mean-field random phase approximation calculation for a two dimensional Fermi liquid with a characteristic energy of 5.0 meV. Furthermore, the IC fluctuations were observed even at room temperature.