Regensburg 2000 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 22: Postersitzung III: Supraleitende Anwendungen (1-4) Massive HTSL, Bandleiter, Filme (5-26), Transport in HTSL (27-30), Elektronenstruktur in Supraleitern (31-43), Borkarbide (44-50), Quantenphasen- und Metall-Isolator-Überg
änge (51-69)
TT 22.33: Poster
Donnerstag, 30. März 2000, 14:00–17:30, A
Observation of out-of-phase bilayer plasmons in YBa2Cu3O7−δ — •M. Grüninger1,2, D. van der Marel1, A.A. Tsvetkov1, and A. Erb3 — 1Lab. of Solid State Physics, MSC, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands — 2II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany — 3DPMC, University of Geneva, CH-1211 Geneva 4, Switzerland
The temperature dependence of the c-axis optical conductivity σ(ω) of optimally and overdoped YBa2Cu3Ox (x=6.93 and 7) is reported in the far- (FIR) and mid-infrared (MIR) range. Below Tc we observe a transfer of spectral weight from the FIR not only to the condensate at ω =0, but also to a new peak in the MIR. This peak is naturally explained as a transverse out-of-phase bilayer plasmon by a model for σ(ω) which takes the layered crystal structure into account. With decreasing doping the plasmon shifts to lower frequencies and can be identified with the surprising and so far not understood FIR feature reported in underdoped bilayer cuprates. The good agreement of the optical data with the multilayer model at all temperatures and doping levels shows that YBCO can be modelled by local electrodynamics along the c-axis in both the normal and the superconducting state. Our results strongly point towards a non-Fermi liquid picture and confinement of carriers to single CuO2 layers. Moreover, implications of the multilayer model for the interpretation of optical data of single layer cuprates are discussed.