Superconducting Dome in Nd_1-xSr_xNiO₂ Infinite Layer Films

We report the phase diagram of Nd_1-xSr_xNiO₂ infinite layer thin films grown on SrTiO₃. A superconducting dome spanning 0.125<x<0.25 is found, remarkably similar to cuprates, albeit over a narrower doping window. However, while cuprate superconductivity is bounded by an insulator for underdoping and a metal for overdoping, here we observe weakly insulating behavior on either side of the dome. Furthermore, the normal state Hall coefficient is always small and proximate to a continuous zero crossing in doping and in temperature, in contrast to the ∼1/x dependence observed for cuprates. This suggests the presence of both electronlike and holelike bands, consistent with band structure calculations.