First-Principles Study of Hole-Doped Superconductors $R$NiO$_2$ ($R$ = Nd, La, and Pr)
Juan-Juan Hao1†, Pei-Han Sun2†, Ming Zhang1, Xian-Xin Wu3,4*, Kai Liu2*, and Fan Yang1*
1School of Physics, Beijing Institute of Technology, Beijing 100081, China 2Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China 3CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China 4Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
Abstract：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 $T_{\rm c}$ 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 $T_{\rm c}$'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).
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2022, Vol. 39 
