EVIDENCE OF SKYRMION EXCITATIONS ABOUT NU=1 IN N-MODULATION-DOPED SINGLE QUANTUM-WELLS BY INTERBAND OPTICAL-TRANSMISSION

A dramatic reduction in the spin polarization of a two-dimensional ele ctron gas in a magnetic field is observed when the Fermi energy moves off the midpoint of the spin gap of the lowest Landau level, v = 1. Th e spin polarization is measured by magnetoabsorption spectroscopy whic h distinguishes the occupancy of the two electron;spin states. The rap id decay of spin alignment over small changes to both higher and lower magnetic field provides experimental evidence for the presence of Sky rmion excitations where exchange energy dominates Zeeman energy in the quantum Hall regime at v = 1.