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TT: Tiefe Temperaturen
TT 6: Postersitzung I (Amorphe- u. Tunnelsysteme, Niedrigdimensionale Systeme, Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter)
TT 6.38: Poster
Montag, 24. März 2003, 14:30–19:00, P2c, P2d
Intrinsic quasiparticle tunneling and pseudogap in layered superconductors and layered manganites — •Heiko Eitel, Timo Nachtrab, Dieter Koelle, and Reinhold Kleiner — Universität Tübingen, Physikalisches Institut - Experimentalphysik II, Auf der Morgenstelle 14, 72076 Tübingen
It is well established that many high temperature superconductors show a reduced density of states at the Fermi level also above Tc, the so-called No-dqpseudogapNo-dq (PG). In addition, the tunneling spectra at temperatures below Tc exhibit a pronounced dip-hump feature. Both observations have been intensively studied but their origin, whether there is a relationship to the superconducting state or not, remains unclear.
We investigated the PG in Bi-2212 single crystals by intrinsic tunneling spectroscopy in magnetic fields up to 7 T and temperatures between 4.2 K and room temperature. We compare these data with similar tunneling experiments on the layered manganite La-327. Here ferromagnetic metallic MnO2 bilayers order antiferromagnetically along the c-axis. Separated by an insulating barrier, they act as an intrinsic stack of spin valves.
There is a striking similarity between the tunneling data obtained for the two systems, suggesting a common origin of the PG.