The spin polarization of 2D electrons in the region 1<ν<2 and a determination of the Composite Fermion mass

We report a study of the spin polarization of the Composite Fermion system in the occupancy range 1<νe<2 equivalent to the occupancy range 1>νh>0 of Composite Fermion holes. Polarized magneto-reflectivity is used to measure the polarization of the unoccupied states in the lowest Landau level. We observe the existence of spin polarized and unpolarized states at View the MathML source and View the MathML source. We measure the polarization of the Composite Fermion gas at View the MathML source from which we can deduce the Composite Fermion mass.