INTERACTION OF ABOVE-FERMI-EDGE MAGNETOEXCITON STATES FROM DIFFERENT SUBBANDS IN DENSE 2-DIMENSIONAL ELECTRON MAGNETOPLASMA

Photoluminescence spectra from δ-doped n-type AlyGa1-yAs/In1-xGaxAs/GaAs quantum wells have been investigated in magnetic fields H≤14 T and T=1.8-18 K. The Fermi level of the quasi-two-dimensional electron gas EF was slightly below the second subband. Interband Landau-level (LL) transitions between the jeth electron LL (je=1,2) and the first hole LL, je-1h, were analyzed. Their intensity was found to increase anomalously when the transition energy intersected that of the magnetoexciton state involving the electron from the second subband, 0e2-0h. The intensity of the 0e2-0h line oscillated with magnetic field and its maxima coincided with the intersection between the 0e2-0h energy and either the je-0h or je-1h transitions or both of them, depending on the energy separation between EF and the second subband. Taking into account that the je-1h and 0e2-0h transitions involve no common particle, the anomalous behavior is explained by the interaction between two magnetoexciton states, 0e2-0h and je-1h. © 1995 The American Physical Society.