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TT: Fachverband Tiefe Temperaturen

TT 22: Low-dimensional Systems - Materials

TT 22.12: Vortrag

Donnerstag, 29. März 2007, 12:30–12:45, H18

Optical response of the ladder compound Sr_2.5Ca_11.5Cu₂₄O₄₁ under high pressure — •S. Frank¹, C. A. Kuntscher¹, R. Klingeler², and B. Büchner² — ¹Experimentalphysik II, Universität Augsburg, D-86159 Augsburg, Germany — ²Leibniz-Institut für Festkörper-und Werkstoffforschung Dresden, PF 27 01 16, 01171 Dresden, Germany

Since the discovery of a pressure-induced superconducting phase, the highly Ca-doped Sr_14−xCa_xCu₂₄O₄₁ two-leg ladder compound is intensively investigated. Based on earlier studies it was suggested that Ca doping [1,2] as well as the application of pressure [3] transfer holes from the chains to the ladders. The nature of the superconductivity, however, remains an open issue.

An important piece of information is how the dynamics of the charge carriers change upon pressure application. We therefore studied the pressure-dependent optical response of Sr_2.5Ca_11.5Cu₂₄O₄₁ over a broad frequency range (far-infrared to visible) at room temperature. Based on these results, we will discuss the possible occurrence of a pressure-induced dimensional crossover in Sr_2.5Ca_11.5Cu₂₄O₄₁ and speculate on the implications of our findings for the superconductivity in this system. Supported by the DFG, Emmy Noether-program. Provision of beamtime at the ANKA Angströmquelle Karlsruhe is acknowledged.

[1] T.Osafune et al., Phys. Rev. Lett. 78, 1980 (1997)

[2] N. Nücker et al., Phys. Rev. B 62, 14384 (2000)

[3] Y.Piskunov et al., Phys. Rev. B 72, 064512 (2006)