In this talk recent Raman scattering data will be presented.
The acquisition of this new data was made possible after a successful growth of
high quality single crystals of (CaLa)₁(BaLa)₂Cu₃O_y. In this YBCO-like compound
the Ca to Ba ratio designate a specific family. Each family has its own phase
diagram, with variation of optimally doped transition temperature, Tc^max, of
about 30%. The Raman scattering peak from magnons is used for the determination
of the superexchange coupling strength, J, in the antiferromagnetic phase. The
Raman peak was measured for several samples from different families. It is found that Tc^max is
proportional to the Raman shift, as measured from different underdoped families
having the same number of holes. It is also found that T_N is proportional to the Raman shift of the fully
underdoped samples. Finally, the method of extracting J from Raman scattering
spectra will be compared to the method of extracting J using muSR.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />