The spin polarization of 2D electrons in the region 1< ν

Abstract

We report a study of the spin polarization of the Composite Fermion system in the occupancy range 1< ν e<2 equivalent to the occupancy range 1> ν h>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 ν e = 5 3 =2− 1 3 and ν e = 4 3 =2− 2 3 . We measure the polarization of the Composite Fermion gas at ν e = 3 2 =2− 1 2 from which we can deduce the Composite Fermion mass.