Absence of electron-phonon-mediated superconductivity in hydrogen-intercalated nickelates

Abstract

A recent experiment [X. Ding, Nature (London) 615, 50 (2023)0028-083610.1038/s41586-022-05657-2] indicates that superconductivity in nickelates is restricted to a narrow window of hydrogen concentration, 0.22<x<0.28 in Nd0.8Sr0.2NiO2Hx. This reported necessity of hydrogen suggests that it plays a crucial role for superconductivity, as it does in the vast field of hydride superconductors. Using density-functional theory and its extensions, we explore the effect of topotactic hydrogen on the electronic structure and phonon-mediated superconductivity in nickelate superconductors. Our calculations show that the electron-phonon coupling in hydrogen-intercalated nickelates is not strong enough to drive the electron pairing, and thus cannot explain the reported superconductivity.