Effect of magnetoexciton correlations on the coherent emission of semiconductors

P. Kner, S. Bar-Ad, M. V. Marquezini, D. S. Chemla, R. Lövenich, W. Schäfer

Research output: Contribution to journalArticlepeer-review


Mean-field, Hartree-Fock theory has been successful in explaining many nonlinear optical experiments in semiconductors. But recently experiments have shown important cases where the mean-field theory (the semiconductor Bloch equations) fails. One such case is bulk GaAs in a strong magnetic field. Here the exciton-exciton interaction can be tuned by varying the magnetic field, providing an excellent method for studying the transition from a regime where mean-field theory is valid to a regime where exciton-exciton correlations must be taken into account. We perform ultrafast time-resolved four-wave mixing on bulk GaAs in a magnetic field, and compare our experimental results with theoretical calculations which go beyond Hartree-Fock theory. We find excellent qualitative agreement. Furthermore, because of the strong correlations that are present, GaAs in a magnetic field presents an excellent opportunity to study the exciton-exciton correlations themselves. We investigate the coherence of the exciton-exciton correlations as the temperature and free-carrier density are varied, and find a surprising sensitivity of the exciton-exciton correlation coherence to these parameters.

Original languageEnglish
Pages (from-to)4731-4748
Number of pages18
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number7
StatePublished - 1999
Externally publishedYes


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