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TT: Tiefe Temperaturen

TT 5: Fachsymposium 1: Unkonventionelle Supraleitung

TT 5.6: Talk

Monday, March 26, 2001, 16:30–16:45, A

LONGITUDINAL AND TRANSVERSE JOSEPHSON PLASMA MODES IN HIGH-T_c SUPERCONDUCTORS — •B. Gorshunov¹, M. Dressel¹, T. Kakeshita², K.M. Kojima², S. Uchida², S. Adachi³, and S. Tajima³ — ¹1.Physikalisches Institut, Universität Stuttgart, Germany — ²Department of Superconductivity, University of Tokyo, Japan — ³Superconductivity Research Laboratory, ISTEC, Tokyo, Japan

Longitudinal and transverse Josephson plasma modes are studied in high-temperature superconductors by optical spectroscopy. For the first time a transverse optical mode is observed in single crystals of T* cuprate superconductors SmLa_0.85Sr_0.15CuO_4−δ and Nd_1.4Sr_0.4Ce_0.2CuO_4−δ which have two different insulating layers sandwiching the superconducting copper-oxygen planes thus forming an alternating array of two inequivalent Josephson junctions. Characteristics of the plasma excitations, like spectral weights and frequency positions, are analyzed based on the existing models.