Structure, heat capacity and Raman spectra of mm-sized Ba$_{2}$MgWO$_{6}$ single crystals synthesized by BaCl$_{2}$-MgCl$_{2}$ flux method

TL;DR

This paper introduces a new flux method for synthesizing large Ba$_{2}$MgWO$_{6}$ single crystals, enabling detailed property measurements and revealing unexpected Raman spectral features suggestive of symmetry breaking.

Contribution

The study develops a novel flux synthesis technique for large Ba$_{2}$MgWO$_{6}$ single crystals and characterizes their structural and vibrational properties.

Findings

High-quality single crystals synthesized successfully.

Heat capacity shows no phase transitions from 300K to 2K.

Additional Raman peaks indicate possible symmetry breaking.

Abstract

We present a new method of Ba$_{2}$MgWO$_{6}$ single crystal synthesis that allows to grow larger crystals using BaCl$_{2}$ and MgCl$_{2}$ flux. Difficulties to grow single crystal of a size suitable for macroscopic material property measurements caused the majority of characterisation being published on polycrystalline samples. Single crystal diffraction and energy dispersive X-ray analysis confirmed high quality of synthesised samples. Heat capacity measurements from 300~K to 2~K do not show any transitions. However, Raman spectra measured down to 77~K contain additional peaks at all temperatures probed, which is in a contrast with only 4 Raman active modes expected from the reducible representation. This calls for a more detailed study of potential symmetry breaking that could also influence the electronic properties of the material.