Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 5: Superconductivity - Mechanisms, Phase Diagram, Competing Order

TT 5.4: Talk

Friday, March 4, 2005, 18:45–19:00, TU H104

Photobleaching in RBa₂Cu₃O_7−δ in a simultaneous Raman and transport experiment — •S. Bahrs¹, A. R. Goñi², J. Guimpel³, B. Maiorov⁴, A. Fainstein³, G. Nieva³, and C. Thomsen¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany — ²ICREA Research Professor, Institut de Ciència de Materials de Barcelona, Campus de la UAB, 08193 Bellaterra, Spain — ³Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, 8400 San Carlos de Bariloche, Río Negro, Argentina — ⁴Superconductivity Technology Center, MS K763, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

Persistent photoinduced change of physical properties in the RBa₂Cu₃O_7−δ high temperature superconductor family has for some time been investigated with various, complemental experimental methods. Illumination induced effects are observed in electrical transport as well as in Raman spectra, and more recently, in reflectance anisotropy spectroscopy. While a connection to oxygen deficiencies in the chain plane of the material is obvious in all experiments, the precise mechanism of photobleaching is still uncertain, nor it is clear if all methods probe aspects of the same physical property of the material.

In this study we focus on the explicit connection between electrical transport and optical phenomena by performing a simultaneous experiment. Both the change of resistivity and Raman features in thin films of GdBa₂Cu₃O_7−δ under illumination have been recorded. We present a comparison of the time dependencies and discuss the results in the framework of the oxygen-vacancy picture of photobleaching.