Parallel suppression of superconductivity and Fe moment in the collapsed   tetragonal phase of Ca0.67Sr0.33Fe2As2 under pressure
  Using non-resonant Fe K-beta x-ray emission spectroscopy, we reveal that Sr-doping of CaFe2As2 decouples the Fe moment from the volume collapse transition, yielding a collapsed-tetragonal, paramagnetic normal state out of which superconductivity develops. X-ray diffraction measurements implicate the c-axis lattice parameter as the controlling criterion for the Fe moment, promoting a generic description for the appearance of pressure-induced superconductivity in the alkaline-earth-based 122 ferropnictides (AFe2As2). The evolution of the superconducting critical temperature with pressure lends support to theories for superconductivity involving unconventional pairing mediated by magnetic fluctuations. 
J. R. Jeffries, N. P. Butch, M. J. Lipp, J. A. Bradley, K.   Kirshenbaum, S. R. Saha, J. Paglione, C. Kenney-Benson, Y. Xiao...
cond-mat.supr-con