Complex structures and electronic phases in simple-oxide thin films

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H05983
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: Tohoku University (2018); Tokyo Institute of Technology (2016-2017)
• Principal Investigator: Yoshimatsu Kohei 東北大学, 多元物質科学研究所, 講師 (30711030)
• Research Collaborator: OHTOMO Akira ; OSHIMA Takayoshi ; SAKATA Osami ; KUMIGAHIRA Hiroshi ; HORIBA Koji
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 酸化物薄膜 / 酸化チタン / 超伝導 / 金属絶縁体転移

Outline of Final Research Achievements

In this research, I focused on reduced simple titanates with their chemical formula of TiOx (x < 2). I grew their titanate films by using pulsed-laser deposition and investigated their electric properties. I succeeded in growth of Ti2O3, gamma-type Ti3O5, and Ti4O7 films. As for Ti2O3 films, I revealed that stable insulating phase and large anisotropy in conductivity due to thin film form. As for gamma-type Ti3O5 and Ti4O7, superconductivity appeared with their transition temperatures of 7.1 K and 3.0 K, respectively.

Free Research Field

酸化物エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

酸化チタン系材料では、二酸化チタン（TiO2)が光触媒や顔料に応用されている。本研究は酸化チタン材料のさらなる応用目指し、電子物性に着目して研究を進めた。その結果、Ti2O3の半導体的特性やTi3O5, Ti4O7の超伝導特性を明らかにした。絶縁体的特性を持つTiO2や金属Tiを含めると、酸化チタン系材料で絶縁体-半導体-金属-超伝導のすべての電子物性が発現することを見出した。すなわち、本研究により安全で安価な酸化チタン材料を用いた「酸化チタンエレクトロニクス」実現の可能性が示された。