Berlin 2005 – scientific programme

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MA: Magnetismus

MA 17: Spinabh
ängiger Transport II

MA 17.5: Talk

Monday, March 7, 2005, 11:30–11:45, TU H1012

Conductance through single atoms: Eigenchannel analysis within the ab initio screened KKR method. — •Alexei Bagrets¹, Nikos Papanikolaou², and Ingrid Mertig¹ — ¹Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany — ²Institute of Microelectronics, NCSR "Demokritos", GR-15310 Athens, Greece

A formalism is presented to evaluate the transmission probabilities and the conductance eigenchannels of atomic-sized contacts from first principles. The approach is based on the ab initio screened KKR method combined with the Kubo Green’s function formulation of the linear response theory. The proposed method is applied to the study of ballistic electron transport through Cu and Pd atomic-sized contacts contaminated by impurities. The nanocontacts are simulated by two semi-infinite crystalline electrodes attached to an atomic cluster of such configuration that a single atom contact is formed. We assume this atom to be (i) a host atom (Cu or Pd), (ii) an sp-impurity (Na, Mg, Al, Si, P and S), and (iii) a 3d impurity. We demonstrate that the conductance of considered systems is mainly determined by the electronic properties of the atom forming the single atom contact. It is shown how the eigenchannels can be classified according to the atomic orbitals of the contact atom, thus leading to the microscopic understanding of the conductance values. In particular, if the pronounced impurity resonances appear at the Fermi energy, it leads either to the opening of the additional channels of the appropriate symmetry or to the reduction of the transmission of the existing channels.