Surface electronic structure of the strongly correlated compound CeCo2P2

The $f$ electrons near the surface of strongly correlated materials show unique properties due to the different environments from those in bulk. Here, we used the density functional theory (DFT) and DFT+dynamical mean field theory method to study the surface electronic structures of the P- and Ce-terminated layer structure of $\mathrm{Ce}{\mathrm{Co}}_{2}{\mathrm{P}}_{2}$. First, we find that the surface states of the paramagnetic P-terminated slab exhibit heavy-fermion behavior. Second, the flat bands of surface $\mathrm{Ce}\text{\ensuremath{-}}4{f}_{5/2}$ in the P-terminated slab was closer to the Fermi level (${E}_{F}$) than that of $\mathrm{Ce}\text{\ensuremath{-}}4{f}_{5/2}$ in bulk and hybridized with $\mathrm{Co}\text{\ensuremath{-}}3d$ conductive bands at low temperature. However, the surface Ce of the Ce-terminated slab was closer to the atomic state because it is in contact with the vacuum, and its strength of hybridization is lower than that of the P-terminated slab, leading to a weaker Kondo resonance peak near ${E}_{F}$. Third, the relaxation of the surface adjusts the dispersion of the bands and enhances the Kondo resonance for the P-terminated slab. Finally, after considering the antiferromagnetic order of Co, we found that the band structure was closer to the experiment results. These results show that $\mathrm{Ce}{\mathrm{Co}}_{2}{\mathrm{P}}_{2}$ is an ideal material for studying interlayer coupling between the two-dimensional Kondo lattice and magnetic layers.