INTRAWELL AND INTERWELL MAGNETOEXCITONS IN INXGA1-XAS GAAS COUPLED DOUBLE-QUANTUM WELLS/

We theoretically study the ground and many of the excited optically ac tive s states of spatially direct (intrawell) and indirect (interwell) quasi-two-dimensional excitons in InxGa1-xAs/GaAs coupled double quan tum wells (DQW's) in quantizing magnetic fields B > 2 T. The evolution of the eigenstates and oscillator strengths with the perpendicular ma gnetic B and electric E fields (when in particular, the direct-indirec t crossover and a number of anticrossings occur in the spectra) is stu died. The results of the theory are in good agreement with the recentl y obtained experimental data [L. V. Butov, A. Zrenner, G. Abstreiter, A. V. Petinova and K. Eberl, Phys. Rev. B 52, 12 153 (1995)]. The phys ical origin of the excitonic symmetric-antisymmetric splittings Delta( x) in DQW's is discussed. It is shown that, in the wide-barrier regime . Is Delta(x) determined by the two-particle tunneling through the bar rier and suppressed by the excitonic effects.