Defect-induced magnetic phase transition of nonmagnetic oxides and device application of defect-induced ferromagnetism

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K22055
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 26:Materials engineering 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): 2019-06-28 – 2021-03-31
• Keywords: 酸化物 / 欠陥強磁性 / ナノ結晶 / ナノ周期構造 / 磁性材料

Outline of Final Research Achievements

Crystals such as zinc oxide and titanium dioxide hardly respond to external magnetic fields. However, when some of the oxygen atoms are lacking (this situation is called oxygen vacancy) while keeping the crystal structure, the crystals become to respond to the magnetic fields rather strongly. The present study partly aims to clarification of mechanism to lead to such a phenomenon, which has not been completely reveled. Also, an attempt was made to fabricate periodic structure of nanosized titanium dioxide because such a structure can interact strongly and uniquely with light. When each of the titanium dioxide nanoparticles has the magnetic properties, such a periodic structure can work as a device which transmits a light signal only in one direction. In the present study, we have successfully fabricated such a periodic structure composed of nanocylinders of titanium dioxide and demonstrated that it uniquely interacts with light.

Free Research Field

無機固体化学

Academic Significance and Societal Importance of the Research Achievements

二酸化チタンを対象に、まずナノメートルサイズの微細な結晶が周期的に規則正しく配列した構造体を作製することから研究を始めた。これは、研究者らの過去の研究で二酸化チタンに酸素空孔を導入すれば、磁場に対する応答が強くなることが分かっているからである。ここでは金属チタンのナノメートルサイズの結晶が規則配列した構造を作り、これを二酸化チタンに変えるという方法を取った。これは新規な手法で、この研究を通じて初めて実現された。この種の構造体は、たとえば光信号を一方向のみに伝達するデバイスなどへの応用が可能である。