The surface state-surface resonance transition on Ta(011)

Abstract

The authors study an unusual surface state-surface resonance transition recently identified in photoemission on Ta(011) using surface electronic structure calculations performed with the surface embedded Green function method. The transition is understood in terms of the relative movement of the bulk bands and surface potential with increasing parallel momentum, which switches the condition for a surface state below the band at the zone centre to a resonance within the band beyond 0.11 AA-1 along Delta . A simple two-band model is constructed to illustrate the effect. Comparison of the calculated and experimental surface bands away from the zone centre shows sizable differences, and the authors predict the existence of several unoccupied surface states which should be visible to inverse photoemission.