Evidence for Skyrmion crystallization from NMR relaxation experiments

A resistively detected NMR technique was used to probe the two-dimensional electron gas in a GaAs/AlGaAs quantum well. The spin-lattice relaxation rate (1/T-1) was extracted at near complete filling of the first Landau level by electrons. The nuclear spin of As-75 is found to relax much more efficiently with T -> 0 and when a well developed quantum Hall state with R-xx similar or equal to 0 occurs. The data show a remarkable correlation between the nuclear spin relaxation and localization. This suggests that the magnetic ground state near complete filling of the first Landau level may contain a lattice of topological spin texture, i.e., a Skyrmion crystal.