Metal-insulator transitions in degenerate Hubbard models and [ital A][sub [ital x]]C[sub 60]

Journal Article · Tue Feb 15 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.5687· OSTI ID:6664493

Lu, J P ^[1]

---

1. Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 (United States)

Analytic results for Mott-Hubbard metal-insulator transitions in [ital N]-fold degenerate Hubbard models are obtained using the Gutzwiller approximation. It is found that for any commensurate filling with integer ([ital x]) electrons per site, there exists a metal-insulator transition at the critical correlation energy [ital U][sub [ital c]]([ital N],[ital x])=[l brace][ [radical][ital x](2[ital N][minus][ital x]+1) + [radical]([ital x]+1)(2[ital N][minus][ital x]) ][sup 2]/(2[ital N][minus][ital x])[r brace][vert bar][bar [epsilon]]([ital x])[vert bar], where [bar [epsilon]] is the energy per particle in the absence of correlation. [ital U][sub [ital c]] increases with [ital x] reaching the maximum at the half filling [ital x]=[ital N]. Therefore, it is possible for a system to be metallic at half filling and insulating away from half filling. This provides an explanation for the unusual metal-insulator transitions observed in fullerides [ital A][sub [ital x]]C[sub 60].

• OSTI ID: 6664493
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:8; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360607* -- Other Materials-- Superconducting Properties-- (1992-)
CARBON
CORRELATED-PARTICLE MODELS
CRYSTAL MODELS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
FULLERENES
HUBBARD MODEL
MATHEMATICAL MODELS
NONMETALS
PARTICLE MODELS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY