Anisotropic spin gaps in BiAg$_2$-Ag/Si(111)
  We present a detailed analysis of the band structure of the BiAg$_2$/Ag/Si(111) trilayer system by means of high resolution Angle Resolved Photoemission Spectroscopy (ARPES). BiAg2/Ag/Si(111) exhibits a complex spin polarized electronic structure due to giant spin-orbit interactions. We show that a complete set of constant energy ARPES maps, supplemented by a modified nearly free electron calculation, provides a unique insight into the structure of the spin polarized bands and spin gaps. We also show that the complex gap structure can be continuously tuned in energy by a controlled deposition of an alkali metal. 
Alberto Crepaldi, Stephane Pons, Emmanouil Frantzeskakis, Klaus Kern,   and Marco Grioni
cond-mat.mtrl-sci cond-mat.other