Large skyrmions in an Al0.13Ga0.87As quantum well

We report tilted-field magnetotransport measurements of two-dimensional ele ctron systems in a 200-Angstrom-wide Al(0.13)Ga(0.87)AS quantum well. We ex tract the energy gap for the quantum Hall state at Landau-level filling v = 1 as a function of the tilt angle. The relatively small effective Lande g factor (g similar or equal to 0.043) of the structure leads to skyrmionic e xcitations composed of the largest number of spins yet reported (s similar or equal to 50). Although consistent with the skyrmion size observed, Hartr ee-Fock calculations, even after corrections, significantly overestimate th e energy gaps over the entire range of our data.