HIGH MAGNETIC-FIELD EFFECTS ON THE DYNAMICS OF EXCITONS IN A GAAS QUANTUM-WELL

The time-resolved photoluminescence of excitons in a 9 nm GaAs/(Al,Ga) As quantum well structure under high magnetic fields (B less-than-or-e qual-to 21 T) applied along the growth direction is reported. Magnetoe xcitons related to the lowest light-hole subband with a well defined o rientation of the magnetic moment are selectively excited. The thermal isation between the two Zeeman split 1 s heavy-hole excition ground st ates is found to be accelerated by the magnetic field. Moreover, a dec rease of the PL rise-time is observed with respect to the zero field c ase where light-hole excitons and the electron heavy-hole continuum st ates are simultaneously excited.