Effects of Ca substitution on the phonon anomalies in the Raman scattering of YBa2Cu4O8
Superconductivity Research Laboratory, International Superconductivity
Technology Center, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062, Japan
Published online: 15 May 2000
We report on the temperature dependence of the frequencies and linewidths in the phonon Raman scattering for system . The phonon anomalies above of the frequencies are observed for the out-of-phase O(2)-O(3) and O(4) modes, and these onset temperatures decrease with increasing Ca content. These features are consistent with the spin-gap behaviors associated with Ca doping reported previously. Furthermore, we find that the smaller gap exists near or just above the Ba phonon frequency at in the undoped samples and its energy increases with Ca doping.
PACS: 74.25.Gz – Optical properties / 74.62.Dh – Effects of crystal defects, doping and substitution / 74.72.Bk – Y-based cuprates
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000