Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 18: Superconductivity - Properties, Electronic Structure, Order Parameter II
TT 18.3: Talk
Monday, March 7, 2005, 10:45–11:00, TU H2053
Mixing between ballistic and diffusive motion in superconducting MgB2 — •Matthias Eschrig1, Kaori Tanaka2,3, Daniel Agterberg4, and Juha Kopu5 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany — 2Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2 — 3Argonne National Laboratory, Argonne, IL 60439, U.S.A. — 4Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53211, U.S.A — 5Low Temperature Laboratory, Helsinki University of Technology, PO Box 2200, FIN-02015 HUT
We introduce a model for the two-band superconductor MgB2 in which the motion of quasiparticles is diffuse in one band (the π-band) and ballistic in the other band (the σ -band). Diffusive and ballistic quasiparticles are coupled by the pairing interaction. We apply this model to examine the electronic structure of vortex cores in MgB2. In particular, we study the effects of impurities on the ballistic motion of quasiparticles in the σ -band in the vortex core region under the presence of the hybridization with the diffusive π-band.We find that the induced superconductivity in the π band results in a core size larger than estimated by HC2 and in weakly bound states, and that those bound states are removed easily by impurities.