Nickelate Superconductivity without Rare-Earth Magnetism: (La,Sr)NiO2

The occurrence of unconventional superconductivity in cuprates has long motivated the search for manifestations in other layered transition metal oxides. Recently, superconductivity is found in infinite-layer nickelate (Nd,Sr)NiO2 and (Pr,Sr)NiO2 thin films, formed by topotactic reduction from the perovskite precursor phase. A topic of much current interest is whether rare-earth moments are essential for superconductivity in this system. In this study, it is found that with significant materials optimization, substantial portions of the La1-xSrxNiO2 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 approximate to 9 K at x = 0.20. Additionally, the unexpected indication of a superconducting ground state in undoped LaNiO2 is observed, which likely reflects the self-doped nature of the electronic structure. Combining the results of (La/Pr/Nd)(1-)xSrxNiO2 reveals a generalized superconducting dome, characterized by systematic shifts in the unit cell volume and in the relative electron-hole populations across the lanthanides.

Automated summary

Through material optimization, a significant portion of the La1-xSrxNiO2 phase diagram can enter the realm of superconductivity, with a maximum onset temperature of approximately 9 K at x = 0.20. An unexpected indication of a superconducting ground state was also observed in undoped LaNiO2. Combining the results of different rare-earth elements in the NiO2 system reveals a generalized superconducting dome characterized by systematic shifts in unit cell volume and electron-hole populations across the lanthanides.