First-Principles Materials Science Research Team

Principal Investigator

PI Name Ryotaro Arita
Degree D.Sci.
Title Team Leader
Brief Resume
2000D.Sci., University of Tokyo
2000Research Associate, Department of Physics, University of Tokyo
2004Postdoctoral Researcher, Max Planck Institute for Solid State Research
2006Research Scientist/Senior Research Scientist, Condensed Matter Theory Laboratory, RIKEN
2008Associate Professor, Department of Applied Physics, University of Tokyo
2011PRESTO, Japan Science and Technology Agency
2014Team Leader, First-Principles Materials Science Research Team, RIKEN Center for Emergent Matter Science (-present)
2016Visiting Professor, Joint Graduate School Program of Frontier Sciences, University of Tokyo

Outline

By means of first-principles methods, our team studies non-trivial electronic properties of materials which lead to new ideas/notions in condensed matter physics or those which have potential possibilities as unique functional materials. Especially, we are currently interested in strongly correlated/topological materials such as high Tc cuprates, iron-based superconductors, organic superconductors, carbon-based superconductors, 5d transition metal compounds, heavy fermions, giant Rashba systems, topological insulators, zeolites, and so on. We aim at predicting unexpected phenomena originating from many-body correlations and establishing new guiding principles for materials design. We are also interested in the development of new methods for ab initio electronic structure calculation.

Research Fields

Physics, Materials Sciences

Keywords

First-principles calculations
Theoretical materials design
Strongly correlated electron systems

Results

Development of density functional theory for unconventional superconductors

Motivated by the recent discovery of superconductivity at 203K in sulfur hydride under extremely high pressure, we performed a fully non-empirical calculation of the superconducting transition temperature (Tc). While the isotope effect suggests that phonons play a crucial role in the high Tc superconductivity, the applicability of the conventional Migdal-Eliashberg theory is a non-trivial problem. Especially for H3S in the Im-3m phase, there is a narrow peak in the density of states around the Fermi level, indicating that the standard Migdal approximation is not applicable. The effects of the zero-point motion and phonon anharmonicity also affect Tc significantly. By considering these effects, we successfully reproduced the experimental Tc from first principles with accuracy of 10K.

   Another characteristic feature in the phase diagram of sulfur hydride is that Tc increases continuously from 50K to 200K around 200GPa. We found an infinite number of metastable crystal structures (the Magneli phase), and succeeded in explaining this peculiar behavior.

Metastable crystal structures in the Magneli phase, which successfully explain why the superconducting transition temperature increases from 50K to 200K continuously.

Members

Ryotaro Arita

Team Leader arita[at]riken.jp R

Shiro Sakai

Research Scientist

Michito Suzuki

Research Scientist

Motoaki Hirayama

Research Scientist

Takuya Nomoto

Special Postdoctoral Researcher

Articles

お問い合わせ

2-1 Hirosawa, Wako, Saitama 351-0198 Japan

E-mail:
arita[at]riken.jp

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