Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 15: Superconductivity: Poster Session
TT 15.48: Poster
Dienstag, 26. Februar 2008, 14:00–18:00, Poster B
Nernst effect of Ni-doped NdBa2Cu3O7−δ — •Niko Johannsen1, Thomas Wolf2, Alexander V. Sologubenko1, Thomas Lorenz1, Axel Freimuth1, and John A. Mydosh1 — 1II. Physikalisches Institut, University of Cologne, Germany — 2Forschungszentrum Karlsruhe, Germany
The mechanism of high-temperature superconductivity is still unsolved. Possible relations to other phenomena such as the pseudogap may play a key role towards an understanding of this mechanism. Using the Nernst effect, we are able to detect vortex-like excitations very sensitively. In NdBa2{Cu1−yNiy}3O7−δ, magnetic Ni-impurities suppress Tc and at the same time enhance the pseudogap. So, this is an ideal system to study possible relations between the pseudogap and superconductivity via the Nernst effect. We present measurements on a series of optimally doped (O7) and two underdoped (O6.8, O6.9) samples with Ni contents ranging from y=0 to 0.12. For the optimally doped samples, the onset temperature of the anomalous Nernst signal (Tν) decreases with increasing Ni content as does Tc. The underdoped (O6.8) samples show a slightly different behavior. Tν is not affected by an increase of the Ni content. The slope of Tν of the intermediate doping level (O6.9) lies between the aforementioned two. None of the detected anomalous vortex Nernst signals shows a relation to the enhanced pseudogap in this system.