Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 18: Superconductivity - Properties, Electronic Structure, Order Parameter II
TT 18.8: Hauptvortrag
Montag, 7. März 2005, 12:00–12:30, TU H2053
Point-Contact Spectroscopy on Conventional and Unconventional Superconductors — •Gernot Goll — Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsruhe, Germany
A growing number of metals is found to exhibit exotic types of superconductivity as manifested by their thermodynamic and transport properties. Unconventional superconductivity is observed in many U- and Ce-based heavy-fermion superconductors and oxide superconductors. Point-contact spectroscopy is one of the tools to study the symmetry and nodal structure of the energy gap Δ. Andreev reflection of charge carriers at the normal metal/superconductor interface leads to minima at V≈ ± Δ /e in the differential resistance dV/dI as a function of applied bias V. In addition, Andreev reflection causes an excess current through the metallic point contact which can be analyzed with respect to the order-parameter symmetry. The talk will review recent developments in this field and focuses on investigations of Sr2RuO4 as a candidate for p-wave superconductivity, and of the heavy-fermion superconductor CeCoIn5 as a possible d-wave superconductor.