Spin polarization and transition from metallic to insulating behavior in 2D systems

Abstract We have made quantitative measurements of the spin polarization of two-dimensional (2D) GaAs (1 0 0) electrons and GaAs (3 1 1) A holes, as a function of an in-plane magnetic field. The functional form of the in-plane magnetoresistance is shown to be intimately related to the spin polarization. Moreover, for three different 2D systems, namely GaAs (1 0 0) electrons, GaAs (3 1 1) A holes, and AlAs (4 1 1) B electrons, the temperature dependence of the in-plane magnetoresistance reveals that their behavior turns from metallic to insulating before they are fully spin polarized.