Raman-active phonons in the high-temperature superconductors and results in ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$Cu${\mathrm{O}}_6$

We report Raman results from single crystals of the 10-K superconductor ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$Cu${\mathrm{O}}_6$, which has one Cu-O plane per primitive unit cell. All $4A_{1g}$ phonons are observed, and the spectrum is very similar to that of the two Cu-O plane phase ${\mathrm{Bi}}_2$Ca${\mathrm{Sr}}_2$ ${\mathrm{Cu}}_2$ ${\mathrm{O}}_8$. This similarity is correlated with the structures of these two materials. A general comparison of the Raman-active modes in all the high-$T_c$ cuprate superconductors is given. This comparison highlights the similarities of the phonon spectra.