Phase diagram of infinite layer praseodymium nickelate Pr_1−xSr_xNiO₂ thin films

We report the phase diagram of infinite layer Pr_1−xSr_xNiO₂ thin films synthesized via topotactic reduction from the perovskite precursor phase using CaH₂. Based on the electrical transport properties, we find a doping-dependent superconducting dome extending between x = 0.12 and 0.28 with a maximum superconducting transition temperature T_c of 14 K at x = 0.18, bounded by weakly insulating behavior on both sides. In contrast to the narrower dome observed in Nd_1−xSr_xNiO₂, a local T_c suppression near x = 0.2 was not observed for the Pr_1−xSr_xNiO₂ system. Normal-state Hall effect measurements indicate mixed carrier contributions of both electrons and holes and show a sign change in the Hall coefficient as functions of temperature and x, quite similar to that in Nd_1−xSr_xNiO₂. Also similar is the observation of a minimum in the normal-state resistivity associated with the superconducting compositions. These findings indicate an infinite layer nickelate phase diagram that is relatively insensitive to the rare-earth element but suggest that disorder arising from the variations of the ionic radii on the rare-earth site affects the superconducting dome.