Synthesis of novel ferromagnetic amorphous oxides and excitation of magnons in them

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K19025
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 36:Inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Tanaka Katsuhisa 京都大学, 工学研究科, 教授 (80188292)
• Co-Investigator(Kenkyū-buntansha): 村井 俊介 京都大学, 工学研究科, 助教 (20378805)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: ランダム系 / 酸化物 / 強磁性 / 希土類 / アモルファス / 固溶体

Outline of Final Research Achievements

The present study aimed to magnetic oxides containing rare-earth ions in random systems. First, borosilicate glasses containing a large amount of Tb3+ ions were prepared, and their glass structures were clarified by utilizing several spectroscopic techniques. Also, the composition of the glass exhibiting a large magneto-optical effect in a short wavelength range at room temperature was suggested. Secondly, magnetic properties of solid solutions of EuZrO3 with alkaline earth metal (Ca, Sr, and Ba) zirconates were explored. It was found that Eu0.7Ba0.3ZrO3 exhibits ferromagnetic transition although the magnetic moments due to the Eu2+ ions are diluted and randomly distributed in the crystal structure. It should be noted that EuZrO3 is antiferromagnetic. It is thought that the replacement of Eu2+ with Ba2+ leads to the expansion of lattice volume and suppresses the antiferromagnetic interaction between Eu2+ ions via 4d orbital of Zr4+.

Free Research Field

固体化学

Academic Significance and Societal Importance of the Research Achievements

酸化物ガラスに代表されるランダム系の酸化物固体に磁気モーメントが導入されると一般にはスピングラス相のような無秩序な磁気構造が現れ、強磁性のような秩序磁性を得ることは難しい。本研究で合成した固溶体の一種であるEu0.7Ba0.3ZrO3はEu2+に付随する磁気モーメントが空間的にランダムに分布しているにもかかわらず強磁性を示すことを明らかにした点は固体化学や固体物理学の基礎の観点から学術的に意義がある。一方、Tb3+高含有ガラスの磁気光学効果は、開発が遅れている可視域から紫外域の光アイソレーターなどを作製する上で実用的に価値のある成果である。