First-Principles Study of Hole-Doped Superconductors RNiO2 (R = Nd, La, and Pr)

Recent experiments have found that in contrast to the nonsuperconducting bulk R NiO 2 ( R = Nd, La, and Pr), the strontium-doped R 1 – x Sr x NiO 2 thin films show superconductivity with the critical temperature T c of 9–15 K at x = 0.2, whose origin of superconductivity deserves further investigation. Based on first-principles calculations, we study the electronic structure, lattice dynamics, and electron–phonon coupling (EPC) of the undoped and doped R NiO 2 ( R = Nd, La, and Pr) at the experimental doping level. Our results show that the EPC-derived T c ’s are all about 0 K in the undoped and doped R NiO 2 . The electron–phonon coupling strength is too small to account for the observed superconductivity. We hence propose that the electron–phonon interaction can not be the exclusive origin of the superconductivity in R NiO 2 ( R = Nd, La, and Pr).