Surface states and their possible role in the superconductivity of MgB 2

We report layer-Korringa-Kohn-Rostocker calculations for bulk and surface states (SFS) as well as the corresponding photoemission intensities of ${\mathrm{MgB}}_{2}.$ Our theoretical results reproduce very well the recent angle resolved photoemission data by Uchiyama et al. [Phys. Rev. Lett. 88, 157002 (2002)]. At least two SFS are assigned. Consequences of SFS on the anisotropy of the upper critical fields and other properties in the superconducting state of grains in micropowder samples are discussed.