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Interband Exchange and the Excitonic Instability
Author(s) -
Kübler J.
Publication year - 1971
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220460129
Subject(s) - instability , condensed matter physics , coulomb , electron , semiconductor , sign (mathematics) , physics , dielectric function , exciton , exchange interaction , band gap , dielectric , quantum mechanics , mathematics , mathematical analysis , ferromagnetism
A calculation of the electronic dielectric function (DF) in semiconductors with small energy gaps is presented that takes into account the screened Coulomb and exchange interaction between electrons and holes. Depending on the sign of the exchange term, the DF is either given approximately by its well‐behaved background value or is strongly enhanced over the RPA result when the gap is decreased to zero. Consequences for the excitonic instability are elaborated.