Structural and electronic response upon hole doping of rare-earth iron oxyarsenides Nd1-xSrxFeAsO (0 < x <= 0.2)

Hole doping of NdFeAsO via partial replacement of Nd3+ by Sr2+ is a successful route to obtaining superconducting phases (T-c = 13.5 K for a Sr2+ content of 20%); however, the structural and electronic response with doping is different from and non-symmetric to that in the electron-doped side of the phase diagram.