Tc is insensitive to magnetic interactions in high-Tc superconductors
  A quarter of a century after their discovery the mechanism that pairs carriers in the cuprate high-Tc superconductors (HTS) still remains uncertain. Despite this the general consensus is that it is probably magnetic in origin [1] so that the energy scale for the pairing boson is governed by J, the antiferromagnetic exchange interaction. Recent studies using resonant inelastic X-ray scattering strongly support these ideas [2]. Here as a further test we vary J (as measured by two-magnon Raman scattering) by more than 60% by changing ion sizes in the model HTS system LnA2Cu3O7-{\delta} where A=(Ba,Sr) and Ln=(La, Nd, Sm, Eu, Gd, Dy, Yb, Lu). Such changes are often referred to as "internal" pressure. Surprisingly, we find Tcmax anticorrelates with J where internal pressure is the implicit variable. This is the opposite to the effect of external pressure and suggests that J is not the dominant energy scale governing Tcmax. 
B. Mallett, G.V.M. Williams, A.B. Kaiser, E. Gilioli, F. Licci, T.   Wolf, J.L. Tallon
cond-mat.supr-con