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arXiv · 2209.05866

Local symmetry breaking and low-energy continuum in K$_2$ReCl$_6 $

P. Stein·T. C. Koethe·L. Bohaty·P. Becker·M. Grüninger·P. H. M. van Loosdrecht
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Abstract

Using polarization selective spontaneous Raman scattering, we have investigated the 5$d$ transition metal compound K$_2$ReCl$_6$ which displays a series of structural phase transitions. We observe a violation of the Raman selection rules in the cubic high temperature phase as well as a low-energy scattering continuum persistent throughout the investigated temperature range from 300 down to 5 K. The continuum couples to one of the phonon modes at temperatures above the lowest structural phase transition at 76 K. We propose a common origin of these observations caused by local fluctuations in the orientation of the ReCl$_6$ octahedra which locally break the long-range cubic symmetry. Consistent results from the related non-magnetic compound K$_2$SnCl$_6$ support this interpretation.

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P. Stein, T. C. Koethe, L. Bohaty, P. Becker, M. Grüninger, P. H. M. van Loosdrecht. 2022-09-13. Local symmetry breaking and low-energy continuum in K$_2$ReCl$_6 $. https://doi.org/10.1103/physrevb.107.214301

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