Linear temperature dependence of conductivity in the apparent insulating regime of dilute two-dimensional holes in GaAs

The conductivity of extremely high mobility dilute two-dimensional holes in GaAs changes linearly with temperature in the insulating side of the metal-insulator transition. Hopping conduction, characterized by an exponentially decreasing conductivity with decreasing temperature, is not observed when the conductivity is smaller than e(2)/h. We suggest that strong interactions in a regime close to the Wigner crystallization must be playing a role in the unusual transport.