Lateral confinement effects of M¯-point Tamm state in vicinal Cu(100) surfaces

Vicinal Cu(100) surfaces with different miscut angles and terrace widths are studied by angle resolved photoemission spectroscopy. The Tamm M¯-point d-like surface state is strongly affected by the super periodic potential induced by the regular array of steps, as it shifts away from the Fermi level and its bandwidth is reduced. For smaller terraces, several replicas are observed, proving that the Tamm surface state is sensitive to the new superperiodic potential. For the largest terraces, the Tamm state starts splitting into incipient and non-dispersing quantum well states, indicating that a transition into a localized regime takes place as a function of terrace width. The results are rationalized using a Kronig-Penney model to simulate the step superperiodicity.