Direct and indirect excitons in diluted magnetic semiconductor double-quantum-wellstructures in external magnetic fields

Abstract

Energy levels and optical transition intensities of direct and indirect excitons in dilutedmagnetic semiconductor double quantum wells were calculated as a function of thestructure parameters and magnetic field. The effects arising from magnetic field inducedcrossing and repulsion of the exciton levels were investigated. Two structures were studied:(Zn, Mn)Se-based and (Cd, Mn)Te-based double quantum wells. In the (Zn, Mn)Se-basedsystem, magnetic field induced level crossing of direct and indirect excitons was found.Above some magnetic field the indirect exciton becomes the lowest excited state of thesystem, which leads to an increase of the exciton lifetime by several orders of magnitude.In the (Cd, Mn)Te-based system, energy level crossing of excitons localized inthe different wells of the structure was found. In this case magnetic field riseleads to transfer of the lowest exciton state from one well to another well of thesystem.