Nonactivated transport of strongly interacting two-dimensional holes in GaAs

We report on the transport measurements of two-dimensional holes in GaAs field-effect transistors with record low densities down to 7x10(8) cm(-2). Remarkably, such a dilute system (with Fermi wavelength approaching 1 mu m) exhibits a nonactivated conductivity that grows with temperature approximately as a power law at sufficiently low temperatures. We contrast it with the activated transport found in more disordered samples and discuss possible transport mechanisms in this strongly interacting regime.