Hall Coefficient of a Dilute 2D Electron System in Parallel Magnetic   Field
  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 $H>H_{sat}$, 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. 
S. A. Vitkalov, H. Zheng, K. M. Mertes, M. P. Sarachik, and T. M.   Klapwijk