Hole doping dependent electronic instability and electron-phonon coupling in infinite-layer nickelates

Recently, charge density waves (CDWs) have been observed in CaCuO2-analogous infinite-layer nickelates RNiO2 (R=La, Nd) but exhibit very different hole doping dependent behaviors compared to that in cuprates, raising a challenging question on its origin. In this paper, employing density functional theory, many-body dynamic mean field theory, and determinant quantum Monte Carlo calculations, we propose a synergetic contribution from both electronic instability (EI) and moment-dependent electron-phonon coupling (MEPC). Unexpectedly, the EI and MEPC are mainly contributed by Ni 3dx2-y2 and R 5dz2, highlighting the unique multiorbital feature. Interestingly, a strong Fermi surface nesting (FSN) induced by the unique feature of van Hove singularity (VHS) across the Fermi level exists in RNiO2, which is sensitive to hole doping. The hole doping can rapidly reduce FSN of Ni 3dx2-y2 by shifting VHS and decrease the occupation of R 5dz2, which can largely weaken EI and MEPC in RNiO2. Remarkably, the temperature-insensitive feature of EI and MEPC could be a hint for rather high-temperature CDWs observed in undoped RNiO2. Our theory may offer one possible explanation to the experimentally observed CDW formation and its hole-doping dependence in nickelates, and also establishes a unified understanding of the hole doping dependent EI and MEPC in nickelates and cuprates.