Spectroscopic Evidence for the Localization of Skyrmions near nu = 1 as T -> 0
04 June 2001
Optically pumped nuclear magnetic resonance (OPNMR) measurements of sup (71) Ga spectra were carried out in an n-doped GaAs/Al sub (0.1) Ga sub (0.9) As multiple quantum well (MQW) sample near the integer quantum Hall ground state nu=1. As the temperature is lowered (down to T ~ 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 nu suggests that the localization is a collective process. The frozen limit spectra appear to rule out a 2D lattice of conventional skyrmions.