Measurements in magnetic fields applied at a small angle with respect to the 2D plane of the electrons of a low-density silicon MOSFET indicate that the Hall coefficient is independent of parallel field from H=0 to H>Hsat, the field above which the longitudinal resistance saturates and the electrons have reached full spin-polarization. This implies that the mobilities of the spin-up and spin-down electrons remain comparable at all magnetic fields, and suggests there is strong mixing of spin-up and spin-down electron states.
@article{arxiv.cond-mat/0008456,
title = {Hall Coefficient of a Dilute 2D Electron System in Parallel Magnetic Field},
author = {S. A. Vitkalov and H. Zheng and K. M. Mertes and M. P. Sarachik and T. M. Klapwijk},
journal= {arXiv preprint arXiv:cond-mat/0008456},
year = {2009}
}