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Charge-density wave formation in Sr_{14}Cu_{24}O_{41}

B. Gorshunov·P. Haas·T. Rõõm·M. Dressel·T. Vuletic·B. Hamzic·S. Tomic·J. Akimitsu·T. Nagata
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Abstract

The electrodynamic response of the spin-ladder compound Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ ($x=0, 3, 9$) has been studied from radiofrequencies up to the infrared. At temperatures below 250 K a pronounced absorption peak appears around 12 cm$^{-1}$ in Sr$_{14}$Cu$_{24}$O$_{41}$ for the radiation polarized along the chains/ladders (${\bf E}\parallel {\bf c}$). In addition a strongly temperature dependent dielectric relaxation is observed in the kHz - MHz range. We explain this behavior by a charge density wave which develops in the ladders sub-system and produces a mode pinned at 12 cm$^{-1}$. With increasing Ca doping the mode shifts up in frequency and eventually disappears for $x=9$ because the dimensionality of the system crosses over from one to two dimensions, giving way to the superconducting ground state under pressure.

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B. Gorshunov, P. Haas, T. Rõõm, M. Dressel, T. Vuletic, B. Hamzic, S. Tomic, J. Akimitsu, T. Nagata. 2002-01-28. Charge-density wave formation in Sr_{14}Cu_{24}O_{41}. https://doi.org/10.1103/physrevb.66.060508

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