Colloquium on May 21st, 2007

Hiroshi Katayama-Yoshida, Osaka University

Computational nano-materials design for semiconductor spintronics

Based upon ab initio electronic structure calculation by Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method within the local-density approximation (LDA), we propose the unified physical picture of magnetism and accurate calculation method of Curie temperature (Tc) in dilute magnetic semiconductors (DMSs) in II-VI and III-V compound semiconductors. We also propose the unified physical picture of magnetism in DMS, where ferromagnetic Zener's double-exchange mechanism (or Zener's p-d exchange mechanism) caused by the partially occupied impurity band and anti-ferromagnetic super-exchange mechanism (or ferromagnetic super-exchange mechanism) is competing to determine the magnetic states in the DMS. We propose the 3-dimensional 3D Dairiseki-phase and 1-dimensional 1D Konbu-phase caused by spinodal nano-decomposition are responsible for high-Tc phase in the inhomogeneous system. We propose the new methodology to go beyond LDA to describe the highly correlated electron system by taking into account the self-interaction correction (SIC) to the LDA