Relation between cuprate superconductivity and magnetism: A Raman study   of (CaLa)(BaLa)$_{2}$Cu$_{3}$O$_{y}$
  We present an investigation of charge-compensated antiferromagnetic (Ca$_{x}$La$_{1-x}$)(Ba$_{1.75-x}$La$_{0.25+x}$)Cu$_{3}$O$_{y}$ single crystals using Raman scattering as well as muon spin rotation. In this system the parameter $x$ controls the Cu-O-Cu superexchange interaction via bond distances and buckling angles. The oxygen content $y$ controls the charge doping. In the absence of doping the two-magnon peak position is directly proportional to the superexchange strength $J$. We find that both $x$ and $y$ affect the peak position considerably. The N\'{e}el temperature determined from muon spin rotation on the same samples independently confirms the strong dependence of the magnetic interaction on $x$ and $y$. We find a considerable increase in the maximum superconducting transition temperature $T_{c}^{max}$ with $J$. This is strong evidence of the importance of orbital overlap to superconductivity in this family of cuprates. 
Dirk Wulferding, Meni Shay, Gil Drachuck, Rinat Ofer, Galina   Bazalitsky, Zaher Salman, Peter Lemmens, Amit Keren
cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el