Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.94: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

Investigation of spin-polarized electron transmission through Co/C/Co tunnel junctions — •Felix Huerkamp, Bernd Stärk, Peter Krüger, and Johannes Pollmann — Institut für Festkörpertheorie, Universität Münster, Germany

We investigate transmission properties of electrons at the interfaces of Co/C/Co metal-semiconductor hybrid systems within an ab-initio approach. The considered open system is a tunnel junction consisting of three parts: the left and right semi-infinite cobalt leads, as well as the scattering region built by N layers of carbon atoms. We employ spin-polarized density-functional theory within the generalized gradient approximation to calculate the spin-polarized transmission. To this end, we use a Greens function technique which is based on the representation of the wave functions by Gaussian orbitals. This enables us to treat the scattering problem as a localized perturbation of a Co crystal. In a first step, we calculate self-consistently the potential in the region of the C layers and the neighboring Co layers. Then we construct the exact self-energies from the potential of bulk Co. Finally, we evaluate the transmission coefficient T(E) calculating the Greens function in the subspace of the perturbation. We have investigated junctions of hexagonal Co with C layers grown in (111) direction, as well as junctions of fcc Co with C layers oriented in (001) direction. The results for the transmission are discussed as a function of the number of C layers in the scattering region.