Nickelate Superconductivity without Rare?Earth Magnetism: (La,Sr)NiO ₂

The observation of superconductivity in infinite layer nickelate (Nd,Sr)NiO$_{2}$ thin films has led to rapid theoretical and experimental investigations these copper-oxide-analogue systems [1-15]. Superconductivity also been found (Pr,Sr)NiO$_{2}$ [16,17], but not previously (La,Sr)NiO$_{2}$ [2], raising a fundamental question whether is associated with the presence rare-earth moments [18,19]. Here we show that significant materials optimization, substantial portions La$_{1-x}$Sr$_{x}$NiO$_{2}$ phase diagram can enter regime coherent low-temperature transport ($x$ = 0.14 - 0.20), subsequent superconducting transitions maximum onset ~ 9 K at $x$ 0.20. Additionally, observe unexpected indication ground state undoped LaNiO$_{2}$, which likely reflects self-doped nature electronic structure. Combining results (La/Pr/Nd)$_{1-x}$Sr$_{x}$NiO$_{2}$ reveals generalized dome, characterized by systematic shifts unit cell volume relative electron-hole populations across lanthanides.