Crystal growth with oxygen partial pressure of the $BaCuSi_2O_6$ and $Ba_{1-x}Sr_xCuSi_2O_6$ spin dimer compounds

TL;DR

This study explores crystal growth of $BaCuSi_2O_6$ and $Ba_{1-x}Sr_xCuSi_2O_6$ compounds under varying oxygen partial pressures, revealing structural stability and enabling future spin dynamics research in these quantum magnetic materials.

Contribution

It introduces a crystal growth method using oxygen partial pressure for these compounds, maintaining tetragonal structure and stability, facilitating advanced magnetic property studies.

Findings

Both compounds grown with enhanced oxygen pressure have stable tetragonal structure.

The mixed system shows no structural phase transition down to low temperatures.

Oxygen partial pressure controls the crystal growth process.

Abstract

$BaCuSi_2O_6$ is a quasi-two dimensional spin dimer system and a model material for studying Bose-Einstein condensation (BEC) of magnons in high magnetic fields. The new $Ba_{1-x}Sr_xCuSi_2O_6$ mixed system, which can be grown with x < 0.3, and $BaCuSi_2O_6$, both grown by using a crystal growth method with enhanced oxygen partial pressure, have the same tetragonal structure ($I4_1/acd$) at room temperature. The mixed system shows no structural phase transition, so that the tetragonal structure is stable down to low temperatures. The oxygen partial pressure acts as control parameter for the growth process. A detailed understanding of the crystal structure depending on the oxygen content will enable the study of the spin dynamics of field-induced order states in this model magnetic compound of high current interest with only one type of dimer layers, which shows the same distance between the Cu atoms, in the structure.