Abstract
The Knight shift of the nuclei is measured in two different electron-doped multiple quantum well samples using optically pumped NMR. These data are the first direct measurements of the electron spin polarization, , near . The data at probe the neutral spin-flip excitations of a fractional quantum Hall ferromagnet. In addition, the saturated drops on either side of , even in a field. The observed depolarization is quite small, consistent with an average of spin flips per quasihole (or quasiparticle), a value which does not appear to be explicable by the current theoretical understanding of the fractional quantum Hall effect near .
- Received 20 January 1998
DOI:https://doi.org/10.1103/PhysRevLett.81.673
©1998 American Physical Society