Characterization of the surface states of Co(0001), Co(111), and ultrathin films of Co on Cu(111)

The surface electronic structure of Co(0001), Co(111), and 2Co/Cu(111) is studied using a parametrized tight-binding Hamiltonian with s, p, and d orbitals in the basis. We compare the calculated local density of states in the vacuum region near the surface with the differential conductance dI/dV obtained with scanning tunneling microscopy (STM). We make a detailed analysis of the band structure in order to settle the origin and nature of spectroscopic and STM features observed on Co surfaces as well as on Co thin films deposited on Cu(111), which have given rise to controversy in recent years.