Impact of Growth Environment on the Crystal Growth and Magnetic and Electronic Properties of Ba2NiWO6 Single Crystals

Abstract

This study introduces the effect of growth atmosphere and pressure on the as-grown crystals and the physical characterization of the double perovskite compound Ba₂NiWO₆ (BNWO). The Ni²⁺ ions form a face-centered cubic (FCC) lattice with an ideal octahedral arrangement. Our growth trials by the floating zone method revealed that BNWO exhibits two distinct colors depending on the growth atmosphere, suggesting that it influences its stoichiometry and phase purity. The antiferromagnetic properties of BNWO align with conventional antiferromagnetic behavior with a J = 1 ground state, as determined by entropy calculation. Additionally, surface photovoltage (SPV) spectroscopy indicates that the impurity levels within the crystal influence the electronic properties of BNWO.

We demonstrate how the growth atmosphere in floating zone synthesis dramatically influences the properties of Ba₂NiWO₆ (BNWO) single crystals. Oxygen and argon atmospheres yield black and brown crystals, respectively, both exhibiting conventional antiferromagnetic behavior with J = 1 ground state. However, surface photovoltage spectroscopy reveals stark differences in their electronic properties: brown crystals show weak absorption, while black crystals display multiple peaks indicative of semiconducting behavior. These findings highlight the critical role of growth conditions in tailoring BNWO’s properties for potential quantum magnetic and optoelectronic applications.