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

Shigenori Utsumi; Seiya Tanaka; Kenichi Maruyama; Nao Hatakeyama; Kenichi Itoh; Jun Koike; Akihiro Horikawa; Hiroki Iriyama; Hajime Kanamaru; Yasushi Amako; Taku Iiyama; Ryusuke Futamura; Ryoji Kiyanagi; Akiko Nakao; Kentaro Moriyama; Yoshihisa Ishikawa; Nobuyuki Momozawa

doi:10.1021/acsomega.0c03671

Flux Growth and Magnetic Properties of Helimagnetic Hexagonal Ferrite Ba(Fe_{1- x} Sc _x )₁₂O₁₉ Single Crystals

ACS Omega. 2020 Sep 17;5(38):24890-24897. doi: 10.1021/acsomega.0c03671. eCollection 2020 Sep 29.

Authors

Shigenori Utsumi^{1

2}, Seiya Tanaka¹, Kenichi Maruyama¹, Nao Hatakeyama², Kenichi Itoh², Jun Koike², Akihiro Horikawa², Hiroki Iriyama², Hajime Kanamaru², Yasushi Amako³, Taku Iiyama³, Ryusuke Futamura³, Ryoji Kiyanagi⁴, Akiko Nakao⁵, Kentaro Moriyama⁵, Yoshihisa Ishikawa⁵, Nobuyuki Momozawa⁶

Affiliations

¹ Graduate School of Engineering and Management, Suwa University of Science, Chino, Nagano 391-0292, Japan.
² Faculty of Engineering, Suwa University of Science, Chino, Nagano 391-0292, Japan.
³ Faculty of Science, Shinshu University, Matsumoto, Nagano 390-8621, Japan.
⁴ J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
⁵ Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan.
⁶ Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.

Abstract

Fabricating large, high-crystalline-quality single-crystal samples of hexagonal ferrite Ba(Fe_1-x Sc _x )₁₂O₁₉ is the first important step to elucidating its helimagnetic structure and developing it for further applications. In this study, single crystals of Ba(Fe_1-x Sc _x )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(Fe_1-x Sc _x )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(Fe_1-x Sc _x )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(Fe_1-x Sc _x )₁₂O₁₉ behaves as a helimagnetic material.