g-factor dependence of the evolution of magneto-optical spectra with the density of quasi-two-dimensional electrons in Cd1-xMnxTe/Cd1-yMgyTe heterostructures

Making use of a unique spin engineering possible in diluted magnetic semiconductors (DMS), we study magneto-optical properties of quantum wells with electrons as a function of their g factor (tuned widely from g(eff)*= - 1.46 to +55). The study is made on samples containing different densities of electrons in various spatial regions of a single structure. An unusual nonmonotonic behavior of the intensity of the trion-related transition is detected. We show that it reflects a reversal of the ordering of the spin-split electron levels with the magnetic field. We provide an experimental evidence that polarization properties of exciton-cyclotron resonances are governed by the spin splitting of the conduction band states only. A very strong band gap renormalization due to the presence of electrons is also determined in our quasi:two-dimensional DMS system. [S0163-1829(99)50816-3].