Scanning tunneling microscopy images of transition-metal structures buriedbelow noble-metal surfaces

We analyze scanning tunneling microscopy (STM) experiments of Ir impurities and chains buried in the subsurface layer of Cu(001) by first-principles c alculations based on the density-functional theory and show for the first t ime that metal atom defect structures below a metal surface can be detected by STM. We show that this is not particular to the Ir/Cu system, but appli es to a much wider class of systems, and holds also for defects in deeper l ayers. For the Ir/Cu system we confirm by total energy calculations that th e subsurface position is energetically the most favorable one.