Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 49: Metal Substrates: Structure, Epitaxy and Growth

O 49.8: Vortrag

Mittwoch, 18. März 2015, 12:15–12:30, MA 042

MD study of gold growth on MnAs — •Andreas Rühl and Christian Heiliger — I. Physikalisches Institut, Justus Liebig Universtität Giessen, D-35392 Giessen, Germany

We present the results of our Molecular Dynamics (MD) study concerning the atomic deposition of gold atoms on different MnAs surfaces. Those growth simulations show a 'layer-plus-island growth', also known as the Stranski-Krastanov (SK) growth. Our research is motivated by the experimental work on ferromagnetic MnAs nanoclusters, which can be easily tuned in different shapes and sizes. Taking two of those clusters and connect them via a non-magnetic metal, for example gold, leads to a GMR-like structure (Giant magnetoresistance).

In order to analyze the structure of the deposited gold atoms, needed for later calculation of the electric transport, we created an EAM potential for the MnAsAu system in the scope of Force Matching by fitting the potential model to ab initio data. The resulting potential is validated by different tests, including the comparison of bulk and surface energies to the corresponding ab initio data. We then carried out growth simulations for different MnAs surfaces and different substrate temperatures. The observed SK-growth exhibits a critical layer thickness at which the island growth starts and by using Bond-Angle analysis we see the gold atoms mainly relaxing to fcc phases.