Dresden 2003 – scientific programme

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TT: Tiefe Temperaturen

TT 9: Neue und unkonventionelle Supraleiter

TT 9.9: Talk

Tuesday, March 25, 2003, 11:30–11:45, HSZ301

Impurity States in Sr₂RuO₄ — •Andreas Poenicke¹, Matthias Eschrig¹, and Mikael Fogelström² — ¹Institut für Theoretische Festkörperphysik,Universität Karlsruhe, 76128 Karlsruhe, Germany — ²Institute of Theoretical Physics, Chalmers University of Technology and Göteborg University, S-41296 Göteborg, Sweden

We investigate impurity states near the chemical potential in the unconventional superconductor Sr₂RuO₄ as a tool to study a possible presence of horizontal line nodes in the order parameter. We assume a triplet order parameter of the form ẑ (k_x+ik_y) f(k_z), where the function f(k_z) describes the modulation of the order parameter along k_z. Impurity scattering is ranging from Born limit to unitary limit. For given scattering cross section, impurity states at the chemical potential occur under the condition that the order parameter modulus is smaller than a critical value in a certain range of k_z. We calculate the corresponding contribution to the density of states and compare our results with low temperature measurements of specific heat and the nuclear magnetic relaxation rate.