Soon-Gun Lee

Surface characteristics of epitaxially grown Ni layers on Al surfaces: Molecular dynamics simulation

The deposition behavior for Ni thin film growth on Al substrates of various orientations according to the incident energy of adatoms was investigated by molecular dynamics simulation. In spite of the low adatom incident energy of 0.1eV, Ni–Al intermixing occurred actively at the surfaces of Al(001), Al(011), and Al(111) at 80K and Ni atoms apparently favored the island growth mode irrespective of the Al surface orientation. The highest surface roughness was shown for the case of Al(111) surface. The steering effect, which results in rougher surface, was significantly observed at low incident energy. The steering effect was quantitatively investigated through the extensive measurement of the trajectory and deposition flux of atoms with the variation of incident energy near the artificially structured Ni step positioned on Al surfaces.

Molecular dynamics investigation of interfacial mixing behavior in transition metals (Fe, Co, Ni)-Al multilayer system

The interface and surface structure of transition metal (TM) (Fe, Co, and Ni) thin film deposited on Al(001) substrate at atomic level were investigated by molecular dynamics simulation. In spite of the low adatom incident energy of 0.1 eV, TM-Al intermixing occurred actively at the surface of Al(001) at room temperature. At the interface region of TM/Al(001), an intermetallic compound was formed and found to be of B2 structure. The Co/Al system showed different layer coverage and pair correlation function characteristics, in comparison with Fe/Al and Ni/Al systems. The different structural and intermixing characteristics at the interface were successfully explained in terms of lattice matching, cohesive energy, and local acceleration effect.

Magnetic, magneto-optical, and transport properties of ferromagnetic shape-memory Ni2MnGa alloy

The magnetic, transport, and magneto-optical properties of Ni2MnGa alloy in the martensitic and austenitic states were investigated. The temperature dependence of resistivity shows kinks at the structural and ferroparamagnetic transitions. The temperature dependence of magnetization was also investigated for both the bulk and the film. It was shown that the lack of crystallinity in the amorphous Ni2MnGa alloy films leads to the loss of ferromagnetic order above 4 K. The nature of the interband absorption peaks in the optical-conductivity spectra and in the absorptive part of off-diagonal components of the dielectric function for the authentic state of Ni2MnGa alloy was elucidated.

The early stage of deposition process for Fe–Cu magnetic multilayer systems: molecular dynamics simulation

The deposition behaviour for a Fe–Cu magnetic multilayer system in an early stage of the deposition process was investigated by molecular dynamics (MD) simulation. Specifically, the steering effect was quantitatively investigated through extensive measurements of the trajectory, deposition flux and force of atoms near the artificially structured Fe or Cu step positioned on the Cu(0 0 1) or Fe(0 0 1) surface. Near the step edges of the planar structure at a low incident energy of 0.1 eV, the steering effect for the case of Fe/Cu(0 0 1) was observed more significantly than for Cu/Fe(0 0 1). Additionally, the mechanism of down-diffusion from the step was discussed and the corresponding energetic was calculated using the molecular statics method.

Energetics of Pb heterostructures formation on the Cu (111) in the early stage of the deposition process

The structural and self-assembling characteristic of Pb heterostructures on the Cu (111) substrate in the early stage of the deposition process were investigated using a molecular dynamics simulation and density functional theory. The Pb islands formed on the Cu (111) surface were observed to diffuse actively in lateral directions following the layer-by-layer growth mode. A heptameric hexagonal island was found to be most stable under highly nonequilibrium conditions. This result can be explained by the tendency of Pb heterostructures, which have minimum surface energy, to have the maximum number of Pb–Pb bondings. In addition, the atomic binding energy, the surface diffusion coefficient prefactor, and the surface diffusion energy barrier for Pb adatoms were quantitatively calculated according to various shapes of Pb islands to determine the stability of the corresponding island.

The Incident Angle Effect of Al Adatom on the Growth Morphology of Al/Ni(001) System: Molecular Dynamics Simulation

The deposition behavior of Al atoms on Ni(001) substrate for various adatom incident angle and incident energy is investigated in this study using molecular dynamics simulation to investigate the growth morphology and the quality of thin film in atomic level. Results show that the surface roughness is comparatively decreased irrespective of adatom incident angle at the incident energy of 6 eV.

The Incident Angle Effect of Al Adatom on the Growth Morphology of Al/Ni

The morphology of Al thin-film growth on an Ni(001) substrate according to the variation incident energy of adatoms was investigated by molecular dynamics simulation. Al atoms apparently favored the layer-by-layer growth mode at a low incident angle. The growth mode of Al film was, however, changed to follow the island growth mode according to the increasing adatom incident angle. Interestingly, the steering effect due to atomic attraction, which results in rougher surface, was significantly observed. The steering effect was quantitatively investigated through the extensive measurement of the trajectory with the variation of incident energy and incident angle near the artificially structured Al step positioned on the Ni surface