Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 6: Niederdimensionale Systeme (incl. Peierls-Übergang, organische Leiter, ...)

TT 6.10: Vortrag

Montag, 8. März 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 Sr_14−xCa_xCu₂₄O₄₁ 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.