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

Recent experiments have found that in contrast to the nonsuperconducting bulk RNiO2(R=Nd,La,and Pr),the strontium-doped R1-xSrxNiO2 thin films show superconductivity with the critical temperature Tc 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 RNiO2(R=Nd,La,and Pr)at the experimental doping level.Our results show that the EPC-derived Tc's are all about 0K in the undoped and doped RNiO2.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 RNiO2(R=Nd,La,and Pr).