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

Superconductivity;Materials Science