Research Interest
Our research is the design of novel materials and their properties by theoretical physics.
In our group, we explore novel materials and their properties using first-principles calculations, which are numerical methods for realistic materials. In particular, we focus on the topological properties of the electronic band structure and search for topological materials with non-trivial properties. We investigate the properties and applications of these unique electronic states. We also include superconducting states and propose the emergence of Majorana fermions. In addition, we develop ab initio methods to treat correlation effects and design a wide range of materials including strongly correlated systems and magnetic systems. We design materials across a wide range of fields, including materials in the chemical and materials fields, such as electrides.
Topological System
- Topological electronic phase - Topological superconducting phase - Topological material and application |
Strongly Correlated System
- Superconductor - Hetero structure |
Ab initio Caluclation
- GW approximation - Effective model from DFT calc. |
Material Science
- Electride - Molecule Crystal - Catalyst |
1. Electrides as a New Platform of Topological Materials
Our group propose electrides as a new platform of topological materials. Electrides are a group of materials in which electron e- exists in the interstitial region and stabilizes the structure as an anion. Electrides are being studied in the field of catalysis because of their small work function. For example, in the layered material Sc2C (Fig. (a)), electrons enter the cavities between the layers and exhibit insulating properties as shown in Fig. (b). The charge density of [Sc2C]2+2e– extends to interlayer positions that are significantly displaced from the Sc2C layer due to the anionic electrons 2e–, resulting in a non-trivial system with a quantized large polarization. Reflecting the bulk topology, a topologically-protected metallic state appears on the Sc2C surface (Fig. (c)). The metallic surface state originates from the interstitial electron, and therefore floats above the Sc2C surface (Fig. (d)). This electron cloud has a small work function, making it possible to use Sc2C as a topological substrate for high-density electron doping. For example, one electron per Mo site can be doped for MoS2 (Fig. (e)). We have discovered a variety of topological electrides including relativistic systems, which will lead to the development of topological properties across scientific fields.
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2. Topological Nodal-line Semimetal and Giant Rashba Splitting
3. Material Design for Strongly Correlated Systems