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TT: Tiefe Temperaturen

TT 15: Postersitzung II: Massive HTSL (1-12), Supraleitung: Anwendungen (13-34), Josephsonkontakte und Kryoelektronik (35-75), Elektronenstruktur und Phononen in HTSL (76-79), Schwere Fermionen, Kondo-Systeme (80-99)

TT 15.77: Poster

Mittwoch, 25. März 1998, 15:00–18:30, D

The evolution of various MIR bands in the infrared spectrum of low doped YBCO — •Markus Grüninger¹, Dirk van der Marel¹, Andreas Erb², and Thilo Kopp³ — ¹Laboratory of Solid State Physics, University of Groningen, The Netherlands — ²DPMC, University of Geneva, Switzerland — ³TKM, University of Karlsruhe, Germany

Various contributions to the optical conductivity of low doped YBa₂Cu₃O_6+x have been analyzed by detailed studies of the dependence on e.g. isotopic mass, doping level, purity of the samples or temperature. We identify different bi-magnon-plus-phonon peaks in undoped YBa₂Cu₃O₆, which allows us to study bi-magnons throughout the entire Brillouin zone and to determine both J and J₁₂. At finite values of doping, several new features arise like magnetic and dielectric polarons, local modes, intra- and interband transitions or Holstein processes. A comparison with several theoretical models is given.