Magneto-optical study of interwell coupling in double quantum wells using diluted magnetic semiconductors

Magneto-optical experiments were carried out on a series of ZnSe/${\mathrm{Zn}}_{1\mathrm{-}\mathit{y}}$ ${\mathrm{Cd}}_{\mathit{y}}$Se double quantum wells coupled by ${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Se diluted magnetic semiconductor (DMS) barriers. The samples consisted of 45-Å nonmagnetic quantum wells with interwell DMS barriers of different thicknesses (10, 35, and 100 Å). The interband ground-state transition, as well as interband transitions between excited states, were observed. As the magnetic field is applied, the heights of the magnetic barriers in the conduction and in the valence band undergo Zeeman shifts, causing major changes in the interwell coupling. Such changes were studied by examining the energies of the transitions, their Zeeman splittings, and their intensities. The dependence of these effects was further studied as a function of temperature and barrier width. The behavior observed in those cases involving ultrathin magnetic barriers was found to be anomalous, and is discussed in terms of effects of reduced dimensionality on the magnetic properties of thin DMS layers. © 1996 The American Physical Society.