Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Density functional theory and beyond for real materials III
O 65.9: Vortrag
Donnerstag, 25. März 2010, 12:30–12:45, H34
Charge transport through O-deficient Au-MgO-Au junctions — •Mohamed Fadlallah1,2, Cosima Schuster1, Udo Schwingenschlögl3, Ivan Rungger4, and Ulrich Eckern1 — 1Universität Augsburg, 86135 Augsburg, Germany — 2Benha University, Benha, Egypt — 3KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia — 4Trinity college, Dublin 2, Ireland
Metal-oxide heterostructures have been attracting considerable attention due to various technological applications as photovoltaic and spintronic devices. We present results of electronic structure and transport calculations for Au/MgO/Au tunnel junctions based on density functional theory and scattering theory on the level of non-equilibrium Green's functions. In particular, we study the dependence of the conductance of the heterostructure on the thickness of the MgO interlayer, the interface termination, and the interface spacing. In addition, we address the effect of O vacancies. The exponential decay with interlayer thickness is modified when Au-O bonds are formed at the interface. Electronic states tracing back to O vacancies change the conductance depending on the position of the vacancy. By increasing the interface spacing, the vacancy induced gap states are shifted towards the Fermi energy, leading to an enhancement of the conductance. Thus, we have identified two mechanisms which determine the conductance of the Au/Mgo/Au-junction: O vacancies are able to increase the transparency of the MgO interlayer; the interface coupling then can be used to fine tune these states.