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

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${}_4$.

6 pages, 2 figures, 3 tables