Materials Functionality Design

Group Web Site

[ Professor ] Masafumi Shirai
Materials Functionality Design

[ Associate Professor ] Kazutaka Abe
Materials Science under Extreme Conditions

[ Assistant Professor ] Masato Tsujikawa

[ Assistant Professor ] Hikari Shinya

[ Research Fellow ] Tufan Roy

[ Research Fellow ] Jun-ichiro Inoue

Research Activities

Various kinds of materials are utilized for processing, communication, and storage of massive data in modern information devices. Our research objectives are as follows: (1) theoretical analyses of quantum phenomena in materials and nanostructures, (2) computational design of materials and nanostructures which possess new functionalities, (3) development of materials design scheme utilizing large-scale computational simulation techniques.

Materials Functionality Design (Prof. Shirai)

Research topics

  • Design of new spintronics materials based on first-principles calculation and machine learning
  • Theoretical analysis of transport properties in spintronics devices
  • Computational simulation of nanostructure growth process in spintronics materilas
  • Development of innovative simulation scheme for material/device functionality design

Our research interest is focused on “spintronics” to realize new functional devices. The main topic is theoretical analysis of spin-dependent transport properties in highly spin-polarized materials. We extend our theoretical research to electric-field effect on magnetic anisotropy in ferromagnetic films for realizing low power-consumption devices. Recently, we seek for new electrode materials of magnetic tunnel junction by combining first-principles calculations and machine learning. We constructed a database containing physical properties of the quaternary Heusler alloy, and successfully created a machine learning model for high-throughput screening of new electrode materials.
To realize semiconductor spintronics materials with novel functionalities, we propose new methods for controlling the magnetic properties and demonstrate materials design of ferromagnetic semiconductors (FMSs), on the basis of the first-principles calculations and model simulations. We also develop first-principles approaches to estimate the transport properties at finite temperature for half-metallic materials and spin-gapless semiconductors.

Fig.1: The correlation between the Curie temperatures of quaternary Heusler alloys predicted by machine learning (horizontal axis) and those obtained by first-principles calculations (vertical axis)

Materials Science under Extreme Conditions(Assoc. Prof. Abe)

Research topics

  • Matter at high densities.
  • Metallization and superconductivity of hydrogen and hydrides.
  • Development of first-principles structural search methods

We investigate the properties of dense materials by using ab initio methods. Our current research focuses on metallic hydrides, which are experimentally found to show high-temperature superconductivity driven by electron-phonon coupling. We are also developing simulation techniques to look for stable structures from first principles. The structure search methods are quite useful for examining unknown substances and, therefore, likewise applicable to designing new materials at one atmosphere.

Fig.2: The “Dairiseki” phase (left) and the “Konbu” phase (right) as a consequence of spinodal nano-decomposition in (In,Fe)Sb FMS