Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 14: Postersitzung III (Neue u. unkonventionelle Supraleiter, Anwendungen der Supraleitung, Dünne Schichten, JJs und SQUIDs, Schwere Fermionen, Kondo-Systeme)
TT 14.8: Poster
Mittwoch, 26. März 2003, 14:30–19:00, P2c
Theory of Excess Current in Sr2RuO4 — •Matthias Eschrig1, Ralph Werner2, Mikael Fogelström3, Frank Laube4, and Gernot Goll4 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany — 2Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe, Germany — 3Institute of Theoretical Physics, Chalmers University of Technology and Göteborg University, S-41296 Göteborg, Sweden — 4Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany
Recent point contact measurements of the unconventional superconductor Sr2RuO4 have revealed a linear dependence of the excess current both on temperature [1] and on an applied magnetic field. The close relation between the temperature and field dependence follows naturally from the observed [2] relation between the critical field and the critical temperature if a well defined dependence of the excess current on the single particle gap, Iexc ∼ Δ1/ν, is assumed. We discuss the experimental results in terms of (a) effects of disorder in a p-wave superconductor, and (b) the presence of a third order phase transition. The latter can be understood as a consequence of fluctuations of internal degrees of freedom of the order parameter.
[1] F. Laube et al., Phys. Rev. Lett. 84, 1595 (2000).
[2] T. Akima, et al., J. Phys. Soc. Jpn. 68, 694 (1999).