Flux Growth and Magnetic Properties of Helimagnetic Hexagonal Ferrite Ba(Fe1– x Sc x )12O19 Single Crystals

Abstract Fabricating large, high-crystalline-quality single-crystal samples of hexagonal ferrite Ba(Fe1–xScx)12O19 is the first important step to elucidating its helimagnetic structure and developing it for further applications. In this study, single crystals of Ba(Fe1–xScx)12O19 of various Sc concentrations x were successfully grown by the spontaneous crystallization method using Na2O–Fe2O3 flux. We determined the optimal starting composition of reagents for Ba(Fe1–xScx)12O19 growth as a function of x. In situ monitoring of the crystal nucleus generation accelerated the success of crystal growth. The obtained crystals comprised black and lamellate structures with a size of 13 mm × 8 mm × 2 mm and a surface of {001} orientation. X-ray diffraction and elemental analysis revealed that the obtained crystals were composed of single-phase Ba(Fe1–xScx)12O19 of high crystalline quality. The lattice constants a and c increased linearly with increasing x, thereby following Vegard’s law. The temperature dependence of magnetization and the magnetization curves at 77 K of the x = 0.128 crystal exhibited behavior characteristics of helimagnetism. Neutron diffraction measurements of the x = 0.128 crystal exhibited magnetic satellite reflection peaks below 211 K, providing evidence that Ba(Fe1–xScx)12O19 behaves as a helimagnetic material.