MAGNETOEXCITON ABSORPTION IN COUPLED QUANTUM-WELLS

A Mott exciton in coupled quantum wells in a transverse magnetic field H is considered. An expression for the exciton spectrum in an arbitra ry magnetic field for large separations D between quantum wells contai ning an electron (e) and a hole (h) is given. The exciton spectrum in a strong magnetic field for different Landau levels at arbitrary D has been calculated. Changes in the parameter DIE, where l= root hc/eH is the magnetic length, cause rearrangement of the magnetoexciton disper sion curves E(P), where P is the conserved ''magnetic'' momentum, whic h is a function of the separation between the electron and hole in the plane of the quantum wells. Off-center (''roton'') extrema occur only for D/l<(D/l)(cr), where (D/l)(cr) is a function of the exciton quant um numbers n and m. The magnetoexciton effective mass in states with m agnetic quantum number m=0 monotonically increases with H and D, while in states with m not equal 0 it is a nonmonotonic function of D/l. Th e probability of generating an exciton in coupled quantum wells increa ses with H. Absorption of electromagnetic radiation due to transitions between excitonic levels in coupled quantum wells is discussed. For a n exciton containing a heavy hole the oscillator strengths f(n1m)(n2m1) increase with H and the oscillator strengths f(n1m)(n2m-1) decrease . (C) 1997 American Institute of Physics.