Dynamic Lattice Distortions in Sr$_2$RuO$_4$: A microscopic study by perturbed angular correlation (TDPAC) spectroscopy

TL;DR

This study uses TDPAC spectroscopy and ab initio calculations to reveal dynamic lattice distortions in Sr$_2$RuO$_4$, linked to spin fluctuations and magnetic instability, providing microscopic insight into its lattice behavior.

Contribution

It provides the first microscopic evidence of dynamic lattice distortions in Sr$_2$RuO$_4$ using TDPAC and ab initio methods, connecting lattice dynamics to magnetic fluctuations.

Findings

Evidence of rapidly fluctuating electric-field gradient (EFG) tensor.

Decrease of main EFG component with decreasing temperature.

Increase of EFG asymmetry below 300 K.

Abstract

Applying time differential perturbed angular correlation (TDPAC) spectroscopy and \emph{ab initio} calculations, we have investigated possible lattice instabilities in Sr$_{2}$RuO$_{4}$ by studying the electric quadrupole interaction of a $^{111}$Cd probe at the Ru site. We find evidence for a dynamic lattice distortion, revealed from the observations of: (i) a rapidly fluctuating electric-field gradient (EFG) tensor of which the main component decreases with decreasing temperature, and (ii) a monotonic increase of the EFG asymmetry ($\eta$) below 300 K. We argue that the observed dynamic lattice distortion is caused by strong spin fluctuations associated with the inherent magnetic instability of Sr$_{2}$RuO$_{4}$.