CaB6: a new semiconducting material for spin electronics.
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.
Tromp
H J
HJ
Faculty of Applied Physics and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
van Gelderen
P
P
Kelly
P J
PJ
Brocks
G
G
Bobbert
P A
PA