Bandgap recovery and electron doping on cleaved [100] surfaces of   divalent semi-metal hexaborides
  This paper has been withdrawn by the authors due to new theoretical evidence and experimental proof that the semiconducting bandgap reported in this paper and ascribed to a surface region is in fact a bulk property of divalent hexaborides. As reported in J. D. Denlinger et al., cond-mat/0107429, which supercedes this paper, bulk-sensitive boron K-edge soft x-ray emission provides a complementary confirmation of the X-point band gap identified by angle-resolved photoemission. 
J. D. Denlinger, J. A. Clack, J. W. Allen, G.-H. Gweon, D. M. Poirier,   C. G. Olson, J. L. Sarrao and Z. Fisk