https://doi.org/10.1007/s100510051096
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
Received:
9
June
1999
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
