Destabilization of the 2D conducting phase by an in-plane magnetic field

We propose a mechanism for the recently reported destabilization by an in-plane magnetic field of the conducting phase of low density electrons in 2D. We apply our self-consistent approach based on the memory function formalism to the fully spin polarized electron system. This takes into account both disorder and exchange-correlation effects. We show that spin polarization significantly favors localization because of the enhancement of the exchange-correlations. A key outcome is that the conducting phase for the fully spin polarized system is significantly suppressed. The in-plane magnetic field needed to stabilize the fully spin polarized state lies in the range 0.1<H<1 T, depending on the carrier density. We determine the metal-insulator phase diagram for the unpolarized and fully polarized systems, and we estimate the dependence of the critical magnetic field on carrier density.