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TT: Tiefe Temperaturen
TT 6: Niederdimensionale Systeme (incl. Peierls-Übergang, organische Leiter, ...)
TT 6.10: Talk
Monday, March 8, 2004, 16:30–16:45, H18
Optical and magneto-optical properties of (Sr,Ca,La)14Cu24O41 — •Philipp Haas1, B. Gorshunov1, M. Dumm1, M. Dressel1, T. Vuletic2, B Korin-Hamzic2, S. Tomic2, and J. Akimitsu3 — 11. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart. — 2Institut za fiziku, HR-10001 Zagreb, Croatia — 3Dep. of Physics, Aoyama-Gakuin University, Tokyo, Japan
The anisotropic optical conductivity of the spin 1/2 2-leg ladder compounds Sr14−xCaxCu24O41 was measured in the frequency range 1 Hz - 300 THz and at temperatures 5 K - 300 K for Ca dopings x=0, 3, and 9. In the undoped sample we discovered a charge-density wave (CDW) along the c direction. Calcium doping suppresses the CDW phase with the transition temperature decreasing from 210K for x=0 to 10 K for x=9. The transport in the chains subsystem was studied in the La-doped compound La3Sr3Ca8Cu24O41. We show that the chain array behaves like a one-dimensional disordered system revealing variable-range-hopping conductivity. In addition the influence of magnetic fields up to 7T on the optical spectra of (Sr,Ca,La)14Cu24O41 at low temperatures was investigated.