MAGNETO-PHOTOLUMINESCENCE STUDY AT A FRACTIONAL QUANTUM HALL REGIME OF CHARGED EXCITONS IN A DILUTE MAGNETIC SEMICONDUCTOR

摘要

We have performed magneto-photoluminescence measurements on modulation doped n-type Cd_(1-x)Mn_xTe/Cd_(1-y)Mg_yTe single quantum wells. In low magnetic fields (the electrons filling factor ν > 1), we observed several photoluminescence lines associated with spin-singlet and spin-triplet charged excitons. In high magnetic fields (ν < 1), we observed only one of the spin-triplet charged excitons that are called as a bright type due to characteristic spin states of electrons and holes in dilute magnetic semiconductor quantum wells, where the photoluminescence intensity increased at a fractional value of ν(=2/3). We consider that the screening effect plays a crucial role for this behavior in high magnetic fields.