Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 15: Superconductivity: Poster Session
TT 15.11: Poster
Dienstag, 26. Februar 2008, 14:00–18:00, Poster B
STM based inelastic electron tunneling spectroscopy on NdBa2Cu3O7−δ — •Pintu Das1,2, Michael R. Koblischka1, Helge Rosner2, Thomas Wolf3, and Uwe Hartmann1 — 1Institute of Experimental Physics, University of Saarland, 66041, Saarbruecken, Germany — 2Max Planck Institute of Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany — 3Forschungzentrum Karlsruhe GmbH, Institute of Solid State Physics, 76021 Karlsruhe, Germany
Inelastic electron tunneling spectroscopy (IETS) is a very powerful tool to detect collective excitations in conducting materials. Due to inelastic excitation by tunneling electrons, a very weak kink is usually observed in dI/dV curves at the bias voltage corresponding to the excitation energy. In IETS on s wave superconductors, phonon modes (ωph) were observed at energies given by E = Δ + ℏ ωph, where Δ is the energy gap. Recently IETS using scanning tunneling spectroscopy (STS) has been used to detect a bosonic mode in Bi2Sr2CaCu2O8+δ [1]. In the STS data obtained on NdBa2Cu3O7−δ single crystals, we observed peaks in d2I/dV2 curves beyond the coherence peaks from which collective excitation energies of ∼ 23 meV and ∼ 34 meV have been found for the samples with Tc of 93.5 K and 95.5 K respectively. Band structure calculation shows that there is no structure in the density of state at the observed energies which thus supports the presumption that the observed kinks in dI/dV curves are due to inelastic scattering of electrons.
[1] Lee et al., Nature 442, 546 (2006).