Eur. Phys. J. B 6, 301-305 (1998)
https://doi.org/10.1007/s100510050552

Temperature dependence of the anisotropic electrodynamics in the ladder compounds Sr_14-xCa_xCu₂₄O₄₁

¹ Laboratorium für Festkörperphysik ETH-Zürich, 8093 Zürich, Switzerland
² Laboratoire de Chimie des Solides, Bâtiment 414, Université de Paris-Sud, 91405 Orsay Cedex, France
³ II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany

Corresponding author: ^a degiorgi@solid.phys.ethz.ch

Received: 18 June 1998
Accepted: 17 July 1998
Published online: 15 December 1998

Abstract

The optical reflectivity as a function of temperature of the title compound for x = 0,5 and 12 has been measured over a broad spectral range from 4 meV up to 12 eV. Our findings suggest a very anisotropic dynamics of the charge excitation spectrum when measuring along or perpendicular to the ladders. Moreover, a metal-insulator transition develops at low temperatures, leading to a suppression of Drude spectral weight in the far and mid-infrared spectral range. We identify this behaviour as a consequence of the localization effects for small Ca substitution, and of the possible formation of a charge density wave condensate for large Ca substitution.