Accessible synthesis of superconducting nickelates via topotactic reduction induced by aluminum sputter deposition

Abstract The discovery of superconductivity in infinite-layer nickelates (IL, ABO 2 ) has opened new avenues for understanding high-temperature superconductivity. However, progress in this field is hindered by significant synthesis challenges and the scarcity of research groups capable of producing superconducting samples. Here, we demonstrate a simple route for the topotactic reduction of nickelates using an aluminum overlayer deposited by sputtering on the precursor material (ABO 3 ), enabling the fabrication of high-quality superconducting Pr 0.8 Sr 0.2 NiO 2 thin films. By systematically optimizing the aluminum deposition parameters, we achieved superconducting samples via in situ or ex situ (after air exposure of the precursor ABO 3 films) reduction. A comparative study of their structural and transport properties shows that in situ Al reduction improves film quality, yielding a maximum superconducting onset transition temperature of 17 K, consistent with the optimal value for this compound. This sputtering-based synthesis route, significantly more accessible than existing methods, offers enhanced control and reproducibility over the reduction process, lowering barriers to the exploration of nickelate superconductors.