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

Abstract

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].

Authors:
 [1]
  1. Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 (United States)
Publication Date:
OSTI Identifier:
6664493
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (United States)
Additional Journal Information:
Journal Volume: 49:8; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FULLERENES; SUPERCONDUCTIVITY; CORRELATED-PARTICLE MODELS; HUBBARD MODEL; CARBON; CRYSTAL MODELS; ELECTRIC CONDUCTIVITY; ELECTRICAL PROPERTIES; ELEMENTS; MATHEMATICAL MODELS; NONMETALS; PARTICLE MODELS; PHYSICAL PROPERTIES; 360607* - Other Materials- Superconducting Properties- (1992-)

Citation Formats

Lu, J P. Metal-insulator transitions in degenerate Hubbard models and [ital A][sub [ital x]]C[sub 60]. United States: N. p., 1994. Web. doi:10.1103/PhysRevB.49.5687.
Lu, J P. Metal-insulator transitions in degenerate Hubbard models and [ital A][sub [ital x]]C[sub 60]. United States. doi:10.1103/PhysRevB.49.5687.
Lu, J P. Tue . "Metal-insulator transitions in degenerate Hubbard models and [ital A][sub [ital x]]C[sub 60]". United States. doi:10.1103/PhysRevB.49.5687.
@article{osti_6664493,
title = {Metal-insulator transitions in degenerate Hubbard models and [ital A][sub [ital x]]C[sub 60]},
author = {Lu, J P},
abstractNote = {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].},
doi = {10.1103/PhysRevB.49.5687},
journal = {Physical Review, B: Condensed Matter; (United States)},
issn = {0163-1829},
number = ,
volume = 49:8,
place = {United States},
year = {1994},
month = {2}
}