Flat bands coupled with magnetism and topological orders near or at the Fermi level are well known to drive exotic correlation physics and unconventional superconductivity. Here, based on first-principles modeling combined with an in-depth symmetry analysis, we reveal the presence of topological flat bands involving low-energy Ni-3dz2 states in the recently discovered superconductor LaNiO2. Our analysis demonstrates that LaNiO2 is an Axion insulator with Z4=2 and that it supports topological crystalline insulating states protected by the glide mirror symmetries. The topological flat bands in LaNiO2 are also shown to host odd-parity superconductivity. Our study indicates that the nickelates would provide an interesting materials platform for exploring the interplay of flat bands, topological states, and superconductivity.
@article{arxiv.2311.03302,
title = {Exposing nontrivial flat bands and superconducting pairing in infinite-layer nickelates},
author = {Ruiqi Zhang and Cheng-Yi Huang and Mehdi Kargarian and Rahul Verma and Robert S. Markiewicz and Arun Bansil and Jianwei Sun and Bahadur Singh},
journal= {arXiv preprint arXiv:2311.03302},
year = {2023}
}