Intensity variation of excitons in magnetically tunable double quantum wells

We have studied a series of ZnSe/Zn1-yCdySe double quantum wells coupled by Zn1-xMnxSe diluted magnetic semiconductor (I)MIS) barriers. Such double qu antum well systems have the advantage that the height of the barrier separa ting the wells can be "tuned" by varying an applied magnetic field, providi ng the experimenter the opportunity to study the effects of coupling betwee n the wells as a function of barrier height continuously in a single struct ure. In this paper, we discuss a new and rather surprising dependence of th e intensities of excitonic transitions observed experimentally as a functio n of the degree of inter-well coupling. These results can be convincingly e xplained by the mixing of single-particle states induced by the Coulomb int eraction and, consequently, by the formation of intra-well and inter-well e xcitons. The results clearly indicate that the role of the Coulomb interact ion is crucial in establishing the nature of exciton states in these struct ures.