Gi-Beom Cha

Strong perpendicular magnetocrystalline anisotropy of bulk and the (001) surface of DO22 Mn3Ga: a density functional study

Strong perpendicular magnetocrystalline anisotropy (MCA) and low saturation magnetization are found in DO22Mn(3)Ga using the full-potential linearized augmented plane wave (FLAPW) method. The ferrimagnetism in the bulk is well preserved in the surfaces of Mn(3)Ga for two possible terminations, where the perpendicular MCA in the (001) direction is greatly enhanced over the bulk, consistent with experiments. Furthermore, the robustness of MCA with respect to lattice strain and a good lattice match with popular substrates suggest that Mn(3)Ga can be a good candidate for strain-resistance spintronics applications.

Magnetism and Magnetocrystalline Anisotropy at fcc Fe (001) Surface

The size and surface effects on the magnetism of a fcc Fe (001) surface was investigated by performing firstprinciples calculations on 3, 5, 7, and 9 monolayers fcc Fe (001) single slabs with two different two-dimensional lattice constants, a = 3.44 A (System Ⅰ) and 3.65 A (System Ⅱ), using the all-electron full-potential linearized augmented plane wave method within a generalized gradient approximation. The surface layers were coupled ferromagnetically to the subsurface layer in both systems. However, the magnetism of the inner layers was quite different from each other. While all the inner layers of System Ⅱ were ferromagnetically coupled in the same way as the surface layer, the inner layers of System I showed a peculiar magnetism, bilayer antiferromagnetism. The calculated spin magnetic moments per Fe atom were approximately 2.7 and 2.9 μ B at the surface for Systems Ⅰ and Ⅱ, respectively, due to the almost occupied Fe d-state being in the majority spin state and band narrowing. The spin orientations of System I were out-of-plane regardless of its thickness, whereas the orientation of System Ⅱ changed from out-of-plane to in-plane with increasing thickness.

Hydrogen physisorption based on the dissociative hydrogen chemisorption at the sulphur vacancy of MoS 2 surface

We provide a new insight that the sulphur-depleted MoS2 surface can store hydrogen gas at room temperature. Our findings reveal that the sulphur-vacancy defects preferentially serve as active sites for both hydrogen chemisorption and physisorption. Unexpectedly the sulphur vacancy instantly dissociates the H2 molecules and strongly binds the split hydrogen at the exposed Mo atoms. Thereon the additional H2 molecule is adsorbed with enabling more hydrogen physisorption on the top sites around the sulphur vacancy. Furthermore, the increase of the sulphur vacancy on the MoS2 surface further activates the dissociative hydrogen chemisorption than the H2 physisorption.

First Principles Calculations on Electronic Structure and Magnetism of Transition Metal Doped ZnO

In this study we investigate the electronic structure and magnetism of transition metal (TM