Fermi surface and surface electronic structure of delafossitePdCoO2

Abstract

We have investigated the Fermi surface (FS) and electronic structure of delafossite ${\text{PdCoO}}_{2}$. We have explored the dependence of electronic structure on the surface termination, considering both ${\text{CoO}}_{2}$- and Pd-terminated ${\text{PdCoO}}_{2}$ slabs. Two FS features are obtained, one larger FS from the Pd-related bulk states and the other smaller one from surface states. The bulk FS is produced mainly by the $\text{Pd}\text{ }4{d}_{3{z}^{2}\ensuremath{-}{r}^{2}}\ensuremath{-}\text{Pd}\text{ }5s$-hybridized state, ${\ensuremath{\Psi}}_{d\ensuremath{-}s}$, which is responsible for the high in-plane conductivity in ${\text{PdCoO}}_{2}$. The surface FS observed in angle-resolved photoemission spectroscopy is found to be produced by the hybridized $\text{Co}\text{ }{t}_{2g}\ensuremath{-}\text{O}\text{ }2p$ surface states for the ${\text{CoO}}_{2}$-terminated ${\text{PdCoO}}_{2}$. Due to the localized nature of the surface states, consideration of the spin-orbit and exchange interactions is essential to describe surface electronic structures near ${E}_{F}$ correctly.