The metallic resistance of a dilute two-dimensional hole gas in a GaAs quantum well: two-phase separation at finite temperature?

We have studied the magnetotransport properties of a high mobility two-dimensional hole gas (2DHG) system in a 10nm GaAs quantum well (QW) with densities in range of 0.7-1.6 × 10 10 cm –2 on the metallic side of the zero-field ‘metal-insulator transition’ (MIT). In a parallel field well above B c that suppresses the metallic conductivity, the 2DHG exhibits a conductivity g ( T ) ≈ 0.3(e 2 /h)ln T reminiscent of weak localization. The experiments are consistent with the coexistence of two phases in our system: a metallic phase and a weakly insulating Fermi liquid phase having a percolation threshold close to B c .