Vibronic excitations in resonant inelastic x-ray scattering spectra of K$_2$RuCl$_6$

TL;DR

This study investigates the dynamic Jahn-Teller effect in K$_2$RuCl$_6$ using RIXS spectra, modeling vibronic states to explain spectral features and their temperature dependence, highlighting the importance of Jahn-Teller coupling.

Contribution

The paper develops a dynamic Jahn-Teller model Hamiltonian for K$_2$RuCl$_6$ and demonstrates its effectiveness in reproducing RIXS spectra, revealing peaks due to Jahn-Teller effects.

Findings

Vibronic states successfully reproduce RIXS spectra

Certain spectral peaks are attributed to Jahn-Teller effects

Temperature dependence of spectra aligns with model predictions

Abstract

We present the fingerprints of dynamic Jahn-Teller effect in resonant inelastic x-ray scattering (RIXS) spectra of K$_2$RuCl$_6$. We determined the dynamic Jahn-Teller model Hamiltonian of an embedded Ru$^{4+}$ ion using post Hartree-Fock methods, and derived the vibronic states by numerically diagonalizing the Hamiltonian. With the obtained vibronic states, we reproduced the RIXS spectra. The shape and the temperature dependence of the RIXS spectrum agree well with the experimental data. We found that some peaks emerge due to the dynamic Jahn-Teller effect rather than the crystal field splitting. Our study indicates the significance of the Jahn-Teller coupling to adequately interpret RIXS spectra.