Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 36: Superconductivity: Properties, Electronic Structure, Order Parameter

TT 36.9: Talk

Friday, February 29, 2008, 12:30–12:45, H 0104

Electron Phonon Interaction and Superconductivity in Nb and Pb investigated with Neutron Resonance Spin Echo Spectroscopy — •Pegor Aynajian¹, Thomas Keller^1,2, Lilia Boeri¹, Klaus Habicht³, and Bernhard Keimer¹ — ¹Max-Planck-Institut für Festkrperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — ²ZWE FRMII, TUM, Lichtenbergstrasse 1, D-85748 Garching, Germany — ³3Hahn-Meitner-Institut, Glienicker Strasse 100, D-14109 Berlin, Germany

The momentum and temperature dependency of the phonon lifetime of the transverse acoustic branches along the [110] and [100] directions in Pb and Nb were studied using the high resolution neutron resonance spin-echo, triple-axis technique. Several anomalies were observed, which can in part be assigned to Kohn anomalies. The most striking feature both in Nb and Pb is a Kohn anomaly sitting at a phonon energy corresponding to the superconducting energy gap 2D(T = 0). This arises the question if 2D is limited by a Kohn anomaly.