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 electron gas in a magnetic field is observed when the Fermi energy moves off the midpoint of the spin gap of the lowest Landau level, n ­ 1. The spin polarization is measured by magnetoabsorption spectroscopy which distinguishes the occupancy of the two electron spin states. The rapid decay of spin alignment over small changes to both higher and lower magnetic field provides experimental evidence for the presence of Skyrmion excitations where exchange energy dominates Zeeman energy in the quantum Hall regime at n ­ 1.