Exploring low-temperature dynamics in triple perovskite ruthenates using nonlinear dielectric susceptibility measurements

Shruti Chakravarty; Sunil Nair

paper

Exploring low-temperature dynamics in triple perovskite ruthenates using nonlinear dielectric susceptibility measurements

arXiv:2307.13448

Abstract

We report the nonlinear dielectric properties of three triple-perovskite ruthenates: Ba $_{3}$ CoRu $_{2}$ O $_{9}$ , Ba $_{3}$ BiRu $_{2}$ O $_{9}$ , and Sr $_{3}$ CaRu $_{2}$ O $_{9}$ . These compounds exhibit notable correlations among their spin, charge, lattice, and polar degrees of freedom. Ba $_{3}$ CoRu $_{2}$ O $_{9}$ displays a pronounced frequency-dependent relaxation in $χ_{2, 3}$ just above the magnetoelastic transition, occurring around 100K, followed by an abrupt loss of polarization within the ordered phase. In Ba $_{3}$ BiRu $_{2}$ O $_{9}$ , we encounter the possibility of multiple coexisting relaxation behaviors, indicating a complex phase strongly influenced by the spin-gap opening at 175K. Lastly, Sr $_{3}$ CaRu $_{2}$ O $_{9}$ displays anomalies with strong dispersion effects close to its magnetic transitions, pointing to a robust coupling between magnetic and dipolar orders in the system. These measurements highlight the significance of higher-order (hyper-)susceptibilities in providing profound insight into the dynamics of a system, offering information otherwise inaccessible through the linear polarization response alone.