Research Theme

Exploration of novel electronic/ionic physical properties using inorganic thin films

Keywords

Inorganic solid-state chemistry, Surface-Interface Science, Solid-state electrochemistry, Materials Informatics

Interfaces exhibit unique phenomena. In transistors, charges can be induced at the interface, leading to applications in electronic devices. In lithium batteries, the movement of lithium is hindered by the interface between the electrode and the electrolyte, which degrades battery performance. We create and model such interfaces to explore novel electronic and ionic properties using thin film technology. For example, we are working on the synthesis of metastable metal hydrides that do not exist in bulk materials, exploring new physical properties by controlling the hydrogen charge state in solids, and elucidating the mechanisms of interface modification to improve performance in fluoride-ion batteries.

Furthermore, to accelerate materials research, we are also working on laboratory automation. Traditionally, materials were carefully synthesized and optimized one by one to evaluate their electronic and ionic properties. In this context, we are introducing robots and AI technologies. The use of robots allows experiments to be conducted in extreme environments, such as inert gas atmospheres or X-ray irradiation conditions, where humans cannot enter. Our goal is to advance the automation of experiments and promote the coexistence of humans and robots in materials research.

Selected Publications

1. Y. Komatsu, R. Shimizu, R. Sato, M. Wilde, K. Nishio, T. Katase, D. Matsumura, H. Saitoh, M. Miyauchi, J. Adelman, R. McFadden, D. Fujimoto, J. Ticknor, M. Stachura, I. McKenzie, G. Morris, W. Macfarlane, J. Sugiyama, K. Fukutani, S. Tsuneyuki, T. Hitosugi, "Repeatable Photoinduced Insulator-to-Metal Transition in Yttrium Oxyhydride Epitaxial Thin Films", Chem. Mater. 34, 3616 (2022).
2. S. Chon, Y. Sugisawa, S. Kobayashi, K. Nishio, M. Wilde, N. Kishi, D. Sekiba, K. Fukutani, T. Hitosugi, R. Shimizu, "Selective Epitaxial Growth of Ca₂NH and CaNH Thin Films by Reactive Magnetron Sputtering under Hydrogen Partial Pressure Control", J. Phys. Chem. Lett. 13, 10169 (2022).
3. R. Shimizu, S. Kobayashi, Y. Watanabe, Y. Ando, T. Hitosugi, "Autonomous materials synthesis by machine learning and robotics", APL Mater. 8, 111110 (2020).
4. R. Shimizu, H. Oguchi, T. Hitosugi, "Metal Hydrides: Epitaxial Growth and Electronic Properties", J. Phys. Soc. Jpn. 89, 051012 (2020).
5. R. Shimizu, K. Sugawara, K. Kanetani, K. Iwaya, T. Sato, T. Takahashi, T. Hitosugi, "Charge-density wave in Ca-intercalated bilayer graphene induced by commensurate lattice matching", Phys. Rev. Lett. 114, 146103 (2015).
6. R. Shimizu, K. Iwaya, T. Ohsawa, S. Shiraki, T. Hasegawa, T. Hashizume, T. Hitosugi, "Atomic-scale visualization of initial growth of homoepitaxial SrTiO₃ thin film on an atomically ordered substrate", ACS Nano 5, 7967 (2011).