Fermi surface and surface electronic structure of delafossite PdCoO2

We have investigated the Fermi surface (FS) and electronic structure of delafossite PdCoO2. We have explored the dependence of electronic structure on the surface termination, considering both CoO2- and Pd-terminated PdCoO2 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 Pd 4d(3z2-r2)-Pd 5s-hybridized state, Psi(d-s), which is responsible for the high in-plane conductivity in PdCoO2. The surface FS observed in angle-resolved photoemission spectroscopy is found to be produced by the hybridized Co t(2g)-O 2p surface states for the CoO2- terminated PdCoO2. 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.