Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 29: Superconductivity: Mechanisms, Phase Diagram, Competing Order
TT 29.1: Vortrag
Donnerstag, 28. Februar 2008, 09:30–09:45, H 3010
Evidence for bulk s and d wave superconductivity and important c-axis involvement in cuprates — Rustem Khasanov1, Alexander Shengelaya2, •Annette Bussmann-Holder3, Hugo Keller1, and K. Alex Müller1 — 1Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland — 2Physics Institute of Tbilisi State University, Chavchavadze 3, GE-0128 Tbilisi, Georgia — 3Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
To clarify the order parameter symmetry of cuprates, the magnetic penetration depth was measured along the crystallographic directions a, b, and c in single crystals of YBa2Cu4O8 via muon spin rotation. This method is direct, bulk sensitive, and unambiguous. The temperature dependences of the penetration depth along the crystallographic a- and b-directions were found to exhibit an inflection point at low temperatures as is typical and provides evidence for two-gap superconductivity (TGS) with s + d wave character in the planes. In contrast, the penetration depth along the c-axis shows almost pure s wave character which never met the awareness of the community thereby highlighting the important role of c-axis effects. We conclude that TGS is a generic and universal feature in the bulk of cuprates.