Spin polarization of 2D electrons in the quantum Hall ferromagnet: evidence for a partially polarized state around filling factor one

We report a study of the spin polarisation of 2D electrons around an occupancy ν=1 for a series of quantum wells with widths ranging from 250 to View the MathML source in which the electron g-factor passes through zero. Our data are inconsistent with present theoretical pictures of the quantum Hall ferromagnet at ν=1 and suggest that a robust collective state forms in the region of ν=1 but that this state does not correspond to full spin polarisation of the system at values of g-factor less than ∼0.5.