Bulk band gaps in divalent hexaborides

Complementary angle-resolved photoemission and bulk-sensitive k-resolved resonant inelastic x-ray scattering of divalent hexaborides reveal a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several models of their novel ferromagnetism. T...

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Bibliographic Details
Published in:Physical review letters 2002-10, Vol.89 (15), p.157601-157601, Article 157601
Main Authors: Denlinger, J D, Clack, J A, Allen, J W, Gweon, G-H, Poirier, D M, Olson, C G, Sarrao, J L, Bianchi, A D, Fisk, Z
Format: Article
Language:English
Subjects:
BORON
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
DEFECTS
ELECTRONS
FERMI LEVEL
FERROMAGNETISM
HEXABORIDE CAB6 ELECTRONIC STRUCTURE
ORIGIN
PHOTOEMISSION
SCATTERING
TRANSPORT
VACANCIES
VALENCE
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Summary:Complementary angle-resolved photoemission and bulk-sensitive k-resolved resonant inelastic x-ray scattering of divalent hexaborides reveal a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several models of their novel ferromagnetism. This semiconducting gap implies that carriers detected in transport measurements arise from defects, and the measured location of the bulk Fermi level at the bottom of the conduction band implicates boron vacancies as the origin of the excess electrons. The measured band structure and X-point gap in CaB6 additionally provide a stringent test case for many-body quasiparticle band calculations.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.89.157601