title: CaB6: a new semiconducting material for spin electronics.
abstract: Ferromagnetism was recently observed at unexpectedly high temperatures in La-doped CaB6. The starting point of all theoretical proposals to explain this observation is a semimetallic electronic structure calculated for CaB6 within the local density approximation. Here we report the results of parameter-free quasiparticle calculations of the single-particle excitation spectrum which show that CaB6 is not a semimetal but a semiconductor with a band gap of 0.8+/-0.1 eV. Magnetism in La(x)Ca1-xB6 occurs just on the metallic side of a Mott transition in the La-induced impurity band.
authors.affiliation: Faculty of Applied Physics and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Tromp
authors.forename: P
authors.initials: P
authors.lastname: van Gelderen
authors.forename: P J
authors.initials: PJ
authors.lastname: Kelly
authors.forename: G
authors.initials: G
authors.lastname: Brocks
authors.forename: P A
authors.initials: PA
authors.lastname: Bobbert