Gapped sliding phononic modes in the incommensurate structure of the ladder-chain system Sr$_{14}$Cu$_{24}$O$_{41}$

ORAL

Abstract

We report on low energy Raman and infra-red (IR) excitations in Sr$_{14}$Cu$_{24}$O$_{41}$. Two modes are observed starting from room temperature in the 1-2 meV range. One is a fully symmetric Raman mode and the other, observed in c-axis reflectance, is an excitation carrying a dipole moment along the chain/ladder direction. We associate these modes with the gapped c-axis sliding motions of the charged, incommensurate CuO$_{2}$ chains and Sr$_{2}$Cu$_{2}$O$_{3}$ ladder layers. This approach is able to quantitatively explain the range and relative energies of these excitations which are sensitive probes of the charge and spin density-wave ordering in the ``14-24-41'' systems.

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Authors

  • Adrian Gozar

    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

  • Christopher Homes

    • Condensed Matter Physics and Materials Science Dept., Brookhaven National Laboratory, Upton, New York
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

  • Girsh Blumberg

    • Department of Physics \& Astronomy, Rutgers University, Piscataway, NJ 08854, USA
    • Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA

  • Verner Thorsmolle

    • Laboratory for Quantum Magnetism, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Switzerland

  • Henrik Ronnow

    • Institute of Condensed Matter Physics, Swiss Federal Institute of Technology, EPFL, CH-1015 Lausanne, Switzerland
    • Laboratory for Quantum Magnetism, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Switzerland