Electronic Structure and Minimal Models for Flat and Corrugated CuO Monolayers: An Ab Initio Study

Slobodchikov, A.A., Nekrasov, I.A., Begunovich, L.V., (...), Korshunov, M.M., Ovchinnikov, S.G.// Materials//

https://doi.org/10.3390/ma16020658

$CuO$ atomic thin monolayer ( $mlCuO$ ) was synthesized recently. Interest in the $mlCuO$ is based on its close relation to ${CuO}_{2}$ layers in typical high temperature cuprate superconductors. Here, we present the calculation of the band structure, the density of states and the Fermi surface of the flat $mlCuO$ as well as the corrugated $mlCuO$ within the density functional theory (DFT) in the generalized gradient approximation (GGA). In the flat $mlCuO$ , the $Cu$ - $3 d_{x^{2} - y^{2}}$ band crosses the Fermi level, while the $Cu$ - $3 d_{x z, y z}$ hybridized band is located just below it. The corrugation leads to a significant shift of the $Cu$ - $3 d_{x z, y z}$ hybridized band down in energy and a degeneracy lifting for the $Cu$ - $3 d_{x^{2} - y^{2}}$ bands. Corrugated $mlCuO$ is more energetically favorable than the flat one. In addition, we compared the electronic structure of the considered $CuO$ monolayers with bulk $CuO$ systems. We also investigated the influence of a crystal lattice strain (which might occur on some interfaces) on the electronic structure of both $mlCuO$ and determined the critical strains of topological Lifshitz transitions. Finally, we proposed a number of different minimal models for the flat and the corrugated $mlCuO$ using projections onto different Wannier functions basis sets and obtained the corresponding Hamiltonian matrix elements in a real space