Papers by Author: Yoon Suk Kim

Abstract: The electronic structure and defect states of 6.25% transition metal (TM = Fe and Co) doped rutile titanium dioxide were investigated by ab initio ultrasoft pseudopotential plane wave method based on density functional theory. When a Fe or Co atom was substituted for a Ti site of TiO2 lattice, additional unoccupied 3d-states of TM appeared as defect states in band-gap and occupied 3d-states represented metallic behavior (half-filled states).It was found that two occupied defect states and one half-filled defect state were the 3d-states of TM from the calculation of band decomposed charge density. The higher unoccupied states were hybridized with unoccupied oxygen 2p-states and located at the middle of band-gap.

Abstract: We used ab initio pseudopotential plane wave methods to study the magnetic and electronic properties of transition-metal doped ¯-SiC. It is found that the SiC:Cr reveals stable ferromagnetism with permanent magnetic moments as large as 2 μB regardless of substitution site. In addition, the SiC:CrSi is predicted to have good electron mobility and wide spin band-gap of 1.58 eV with the Fermi level at the center of the gap, which is desirable for realizing spintronic devices.