Unconventional Metallicity and Giant Thermopower in a Strongly   Interacting Two Dimensional Electron System
  We present thermal and electrical transport measurements of low-density (10$^{14}$ m$^{-2}$), mesoscopic two-dimensional electron systems (2DESs) in GaAs/AlGaAs heterostructures at sub-Kelvin temperatures. We find that even in the supposedly strongly localised regime, where the electrical resistivity of the system is two orders of magnitude greater than the quantum of resistance $h/e^2$, the thermopower decreases linearly with temperature indicating metallicity. Remarkably, the magnitude of the thermopower exceeds the predicted value in non-interacting metallic 2DESs at similar carrier densities by over two orders of magnitude. Our results indicate a new quantum state and possibly a novel class of itinerant quasiparticles in dilute 2DESs at low temperatures where the Coulomb interaction plays a pivotal role. 
Vijay Narayan, Srijit Goswami, Michael Pepper, Jonathan Griffiths,   Harvey Beere, Francois Sfigakis, Geb Jones, Dave Ritchi...
cond-mat.str-el