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A First-principles Study on Magnetism of Al Impurity in bcc Fe
Gul Rahman,In Gee Kim 한국자기학회 2011 Journal of Magnetics Vol.16 No.1
The magnetism and electronic structure of bcc Al₁Fe₂? was investigated by means of first-principles calculations with and without spin-orbit coupling (SOC). From the calculated total energy, the SOC corrected system is shown to be approximately 5 meV per atom lower than the SOC uncorrected system. The induced spin magnetic moment at the Al site was ?0.125 μB without SOC and ?0.124 μB with SOC. The orbital magnetic moments were calculated to be 0.002 μB in [100] direction for Al. The electronic structures showed the nearest neighbor antiferromagnetic interaction between Fe and Al to be essential for determining the magnetism of the Al₁Fe₂? system.
Magnetism of Zinc-Blende Fe Chalcogenides (FeY, Y = S, Se and Te): First-Principles Calculations
Gul Rahman,Sunglae Cho,Soon Cheol Hong 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1
Within the framework of density functional theory (DFT) in the generalized gradient approximation (GGA) using the full potential linearized augmented plane wave (FLAPW) method, we study the magnetism and the electronic properties of zinc-blende (ZB) Fe chalcogenides. The theoretical calculations show that the magnetic ground states of all of the ZB FeS, FeSe and FeTe considered in this study are antiferromagnetic (AFM). The calculated equilibrium lattice constant of ZB Fe chalcogenides in the AFM states varies linearly with the ionic radius of anion. The calculated density of states shows that these Fe chalcogenides are metals.
Electronic and magnetic properties of digitally Ti doped InP: A first principles study
Rahman, Gul,Cho, Sunglae,Hong, Soon Cheol WILEY-VCH Verlag 2008 Physica status solidi. PSS. A, Applications and ma Vol.205 No.8
<P>Using the full-potential linearized augmented plane wave method within the generalized gradient approximation, we study the electronic and the magnetic properties of digitally Ti doped InP. It is quite interesting that digitally Ti-doped InP system shows half metallic ferromagnetism even though both bulk zinc blende TiP and InP are paramagnetic. We also investigate the electronic and the magnetic properties as a function of spacer layer thickness. Their properties such as exchange coupling constant and atomic projected density of states are more or less independent of the InP thickness. Spin density contour maps indicate that the spin-polarization is confined within the TiP plane. The system may show a highly anisotropic property in spin-polarized transport. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Magnetic Properties of Anti-Perovskite Tetracobalt-Nitride Surfaces: a First-Principles Study
Gul Rahman,김인기,Lee-Hyun Cho,Beata Bia lek,이재일 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
We investigate the magnetic properties of the Co4N (001) surface by using the full-potential linerized augmented plane-wave band method. We consider two posible terminations, i.e., Co-atom-terminated and CoN-atom-terminated surfaces. From the calculations of the magnetic moment and the site-projected spin-polarized density of states of each atom in the systems, which remain very similar to the properties of the Co4N bulk structure, we find that surface termination does not influence considerably the magnetic properties of deeper layers in the anti-perovskite (001) surface. The properties of Co atoms in the two outermost layers depend on their position in the unit cell. Co1-type atoms, which are at the corners of a cubical unit cell, are distant from N atoms and they retain an isolated character as the Co atoms in Co fcc crystal Co -type atoms, which occupy the center of the cube faces, interact more strongly with neighboring N atoms. Therefore, the magnetic moment on atoms is smaller than that on atoms at the surface layer (S). Compared to the values of magnetic moments on the corresponding atoms in the bulk structure, the magnetic moments on the surface (S) and (S) atoms are larger: CO 2.01 and 1.55 Ub, respectively. In the CoN-terminated surface, the value obtained for Co (S) is 1.61 ub . The magnetic properties of the Coatoms, which are barely influenced by the presence of N atoms, do not depend much on the surface termination.
A First-principles Study on Magnetic and Electronic Properties of Ni Impurity in bcc Fe
Gul Rahman,In Gee Kim 한국자기학회 2008 Journal of Magnetics Vol.13 No.4
The magnetic and electronic properties of Ni impurity in bcc Fe (Ni₁Fe26) are investigated using the full potential linearized augmented plane wave (FLAPW) method based the generalized gradient approximation (GGA). We found that the Ni impurity in bcc Fe increases both the lattice constant and the magnetic moment of bcc Fe. The calculated equilibrium lattice constant of Ni₁Fe26 in the ferromagnetic state was 2.84 A, which is slightly larger than that of bcc Fe (2.83 A). The averaged magnetic moment per atom of Ni₁Fe26 unit cell was calculated to be 2.24 μB, which is greater than that of bcc Fe (2.17 μB). The enhancement of magnetic moment of Ni₁Fe26 is mainly contributed by the nearest neighbor Fe atom of Ni, i.e., Fe1, and this can be explained by the spin flip of Fe1 d states. The density of states shows that Ni impurity forms a virtual bound state (VBS), which is contributed by Ni eg↓ states. We suggest that the VBS caused by the Ni impurity is responsible for the spin flip of Fe1 d states.