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Large perpendicular magnetic anisotropy of ultrathin Ru and Rh films on a NiAl(001) surface
Kim, Dongyoo,Yang, JeongHwa,Hong, Jisang IOP Pub 2010 Journal of Physics, Condensed Matter Vol.22 No.42
<P>Using the full potential linearized augmented plane wave (FLAPW) method, the magnetic properties of two-dimensional Ru and Rh monolayers (MLs) on a NiAl(001) surface have been investigated. It has been found that free standing one monolayer Ru and Rh films have ferromagnetic ground state with magnetic moments of 2.21 and 1.48 μ<SUB>B</SUB>, respectively. The ferromagnetism is still observed even on a Ni terminated NiAl(001) surface, while no magnetic state is found on an Al terminated surface. The calculated magnetic moments of Ru and Rh atoms are 1.56 and 0.88 μ<SUB>B</SUB>, respectively. In addition, an induced magnetic moment in surface Ni is observed. It has been found that the free standing Ru film has perpendicular magnetization to the film surface with a magnetocrystalline anisotropy (MCA) energy of 0.66 meV/atom, while an in-plane MCA energy of 0.37 meV/atom is achieved in Rh film. Very interestingly, we find that both Ru/NiAl(001) and Rh/NiAl(001) films have perpendicular magnetic anisotropy and the calculated MCA energies are 0.66 and 1.11 meV in Ru/NiAl(001) and Rh/NiAl(001), respectively. Along with the magnetic anisotropy, we have presented theoretically calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) results. </P>
Ultrathin half metallic N and antiferromagnetic semiconducting C layers on MgO(001)
Kim, Dongyoo,Yang, JeongHwa,Hong, Jisang IOP Pub 2010 Journal of physics, an Institute of Physics journa Vol.22 No.48
<P>Using the full potential linearized augmented plane wave (FLAPW) method, we have explored the magnetic properties of ultrathin C and N layers on a MgO(001) surface. It has been found that the free standing C layer has a ferromagnetic (FM) ordering with a magnetic moment of 0.82 μ<SUB>B</SUB>, while the free standing N layer with the same coverage displays an antiferromagnetic (AFM) state with a magnetic moment of 1.68 μ<SUB>B</SUB>. Through a structure optimization procedure, we have found that both C and N adatoms are adsorbed on the O-top position in the presence of a MgO(001) surface. The ultrathin 0.25 monolayer coverage of C/MgO(001) film becomes a magnetic semiconductor and shows the c(2 × 2) AFM ground state with a magnetic moment of 0.62 μ<SUB>B</SUB>. Surprisingly, the ultrathin N/MgO(001) manifests a half metallic state with a magnetic moment of 0.47 μ<SUB>B</SUB>. In addition, the induced spin polarization in the O atom is found and this hybridization significantly affects the density of states (DOS) behavior. This peculiar DOS feature results in the opposite magnetic ground states of C and N layers on a MgO(001) surface. Additionally, it is found that the N/MgO(001) has a perpendicular magnetocrystalline anisotropy energy of 63 µeV. We also present theoretically calculated x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) results. </P>
Magnetic Properties of Fe/Ni Thin Films : First Principles Study
Dongyoo Kim,Jisang Hong 한국자기학회 2008 Journal of Magnetics Vol.13 No.2
This study examined the magnetic properties of ultrathin Fe/Ni films on a Cu(001) surface using the full potential linearized augmented plane wave (FLAPW) method. The magnetic moment of Fe/Ni films was found to be insensitive to strain. Nevertheless, strain had a significant influence on the magnetization direction. For example, Fe/Ni films showed a thickness-dependent spin reorientation transition in the presence of strain, while the Fe/Ni films grown pseudomorphically on Cu(001) always showed perpendicular magnetization. In addition, the theoretically calculated X-ray magnetic circular dichroism (XMCD) was examined.