We present extensive magnetic measurements of the (Ca_xLa_{1-x})(Ba_{1.75-x}La_{0.25+x})Cu_{3}O_{y} (CLBLCO) system with its four different families (x) having a Tc^max(x) variation of 28% and minimal structural changes. For each family we measured the Neel temperature, the anisotropies of the magnetic interactions, and the spin glass temperature. Our results exhibit a universal relation Tc=c*J*n_s for all families, where c~1, J is the in plane Heisenberg exchange, and n_s is the carrier density. This relates cuprate superconductivity to magnetism in the same sense that phonon mediated superconductivity is related to atomic mass.
@article{arxiv.cond-mat/0606695,
title = {A magnetic analog of the isotope effect in cuprates},
author = {Rinat Ofer and Galina Bazalitsky and Amit Kanigel and Amit Keren and Assa Auerbach and James S. Lord and Alex Amato},
journal= {arXiv preprint arXiv:cond-mat/0606695},
year = {2009}
}