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O: Oberflächenphysik
O 33: Nanostrukturen II
O 33.3: Vortrag
Donnerstag, 27. März 2003, 15:30–15:45, FOE/ORG
Atomic bridges: structure, electronic and magnetic properties — •V.S. Stepanyuk1, P. Bruno1, A.I. Klavsyuk2, A.N. Baranov2, W. Hergert2, and I. Mertig2 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — 2Fachbereich Physik, Martin-Luther-Universität, Halle-Wittenberg, Friedemann-Bach-Platz 6, D-06099 Halle, Germany
Quantum point contacts are structures in which a neck of atoms just a few atomic diameters wide bridges two electrodes. We apply the density functional theory and the screened Korringa-Kohn-Rostoker (KKR) Green’s function method to study electronic and magnetic properties of atomic bridges in a fully relaxed geometry. Relaxations of bridges and electrodes are performed using an ab initio based many body potentials formulated in the tight binding approximation. We concentrate on Cu, Co, Rh and Pd atomic bridges. The variation of stress in bridges with elongation is calculated. Atomic rearrangements before the breaking are revealed. We show that the largest atomic displacements take place in the electrodes, not in the bridge itself. We demonstrate the interplay between the structure of atomic bridges and the electronic states. Our results show that the atomic relaxations can drastically influence the local density of electronic states (LDOS) and may lead to the jump in LDOS at the Fermi level before the breaking. The standing-wave patterns that are confined within the 1D bridges allows one to explain the changes in the electronic states of bridges caused by the atomic relaxations. We demonstrate that the atomic bridges constructed from non-magnetic in bulk Rh and Pd can be magnetic.