Spectroscopic evidence for the localization of skyrmions near ν=1 as T → 0

Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample near the integer quantum Hall ground state v = 1. As the temperature is lowered (down to T approximate to 0.3 K), a tilted plateau emerges in the Knight shift data, which is a novel experimental signature of quasiparticle localization The dependence of the spectra on both T and v suggests that the localization is a collective process. The frozen limit spectra appear to rule out a 2D lattice of conventional Skyrmions.