Behavior of excitonic levels in symmetric and asymmetric double quantum wells in a magnetic field

We studied theoretically the excitonic energy levels and the optical absorption spectra for double quantum wells, both symmetric and asymmetric, in the presece of an homogeneous magnetic field. Within the effective mass approach, we expanded the excitonic wave function, in an orthogonal basis formed by products of electron and hole wave functions in the growth direction z, and one particle solutions of the magnetic Hamiltonian in the x-y plane. We applied our method to the case of Al_xGa_{1-x}As, for which we showed how the exciton wave function vary, and how the basis functions are mixed in a non trivial way by the effect of the Coulomb potential. By taking into account all the mixing between the elements in our base, we get anti-crossing between excited excitonic states not reported previously.