ICMCTF2005 Session TP: Symposium TS Poster Session
Thursday, May 5, 2005 5:00 PM in Room Town & Country
Thursday Afternoon
Time Period ThP Sessions | Topic TS Sessions | Time Periods | Topics | ICMCTF2005 Schedule
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TP-1 Theoretical Calculations on Atomistic Behaviors in Transition Metals (Fe, Co, Ni)-Al Multilayer System: Ab initio Approach
C. Kim, Y.-C. Chung (Hanyang University, South Korea) As the thickness of the metal layers in the magnetic multilayer becomes within the nm scale, the magnetic properties are remarkably affected by the morphology of the interface. Recent reports of transition metals (TMs)-Al system such as Fe-Al, Co-Al and Ni-Al reveal that the tendency of mixing behaviors is significantly different for each system. Since the intermixing characteristics of constituent atoms strongly govern the magnetic properties of multilayer system, in this study, the atomistic behaviors such as diffusion and incorporation process for the TM-Al systems were quantitatively investigated using ab initio calculations. The calculated energy barriers for the surface diffusion of adatom were 0.89 eV for Fe/Al(001), 1.01 eV for Co/Al(001) and 1.98 eV for Ni/Al(001) system. These values were much larger than the Al/TM (001) (0.64 eV for Al/Fe, 0.73 eV for Al/Co and 0.76 eV for Al/Ni) systems. The energy barriers for the incorporation of Fe, Co and Ni adatom into the Al substrate were calculated to be 0.38 eV, 0.39 eV and 0.29 eV. However, the Al adatom required relatively large energy barrier, 0.99 eV, 1.28 eV and 0.82 eV for the incorporation into the Fe, Co and Ni substrate, respectively. Additionally, in order to verify the change of bonding nature accompanied by the movement of adatom and substrate atoms, the displacement of constituent atoms was quantitatively analyzed. |
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TP-2 Atomic Investigation of Al/Ni(001) by Molecular Dynamics Simulation
S.-G. Lee, Y.-C. Chung (Hanyang University, South Korea); K.-R. Lee (Korea Institute of Science and Technology, South Korea) The interfacial feature of Ni-Al magnetic metallic multilayer (MML) system was quantitatively investigated using molecular dynamics simulation. It is known that various compounds are thermodynamically stable between Ni and Al. Therefore, structural and compositional variation at the interface are predicted in making Ni-Al MML of nanometer scale, and the variation at the interface is eventually going to have an effect on the magnetic property of devices. In this work, to analyze the interface characteristics on an atomic scale according to deposition conditions, the substrate temperature was varied from 300 K to 1000 K and the kinetic energy of incident atoms was kept to 0.1 eV. This system was relaxed for each additional adatom in the limit of 200 pico-second. When Al atoms of 0.1 eV were deposited on Ni(001) substrate, it was found that a pair of elements, which is immiscible in the bulk, formed a mixture confined to a single atomic layer at the surface and stable Ni3Al compound was found in the interface region at about 1000 K. Decreasing the deposition rate, more distinct Ni3Al compound was found at the interface. The nearest neighbor distance between Ni and Al atoms and the layer coverage of the deposited layers are quantitatively analyzed to investigate the effect of the substrate temperature and the deposition rate of the Al adatom on the interfacial characteristics. |
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TP-3 Bonding and Classification of Nanolayered Ternary Carbides
Z. Sun, D. Music (RWTH Aachen University, Germany); R. Ahuja, S. Li (Uppsala University, Sweden); J.M. Schneider (RWTH Aachen University, Germany) We have investigated the elastic properties of nanolayered M2AC with M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and A = Al, Ga, Ge, Sn by ab initio calculations. We suggest that M2AC can be classified into two groups: One where the bulk modulus of the binary MC is conserved and another group where the bulk modulus is decreased. This classification can be understood in terms of coupling between MC and A layers which is defined by the valence electron population. These results may have implications for understanding of properties and performance of this class of solids. |
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TP-4 Molecular Dynamics Simulation of Nano-Scale Fe-Al Thin Film Growth
C.-Y. Chung (Hanyang University, South Korea); K.-R. Lee (Korea Institute of Science and Technology, South Korea); Y.-C. Chung (Hanyang University, South Korea) The interfacial feature and growing morphology of Fe-Al magnetic metallic bilayer system was quantitatively investigated using molecular dynamics simulation. Interfacial intermixing and surface morphology are eventually going to have effect on the magnetic property of devices. In this work, in order to investigate the interface characteristics and growth morphology, Fe atoms were deposited on the Al(001) substrate. The optimized EAM potential for Fe-Al system was adapted to a molecular dynamics code, XMD. The substrate temperature was kept at 300K and 500K and the kinetic energy of incident atoms was varied from 0.1 eV to 3.0 eV. At the interface region, intermetallic compound was found to be B2 structure in the same manner as Co/Al system. However, Fe/Al system has shown different characteristics comparing to other ferromagnetic/non-ferromagnetic metallic bilayer systems such as layer coverage function and mixing length. The different intermixing behavior could be successfully explained in terms of cohesive energy, local acceleration, and lattice matching. |