Fig. 2
Metallic surface with insulating CEFL bulk. The bulk realizes a CEFL, a compensated semi-metal with particle and hole-like pockets (as shown in Fig. 1c), that have both fCE and spinon-like character (see Fig. 1a, b for a carricature of the excitations). Upon approaching the surface, it possible for the fCE to unbind as a result of reduced U df /t d in a region of typical size ~ξ, thereby liberating the d–electrons and holons, which may Bose condense. The latter leads to confinement and the resulting state is then a decoupled metallic surface. Only the top and bottom surfaces are shown for clarity
