Interplay between disorder and interactions in two dimensions

The interplay between Coulomb interactions and randomness has been a long-standing problem in condensed matter physics. Recent thermodynamic and transport experiments have shown that in clean two-dimensional electron systems, strong interactions between carriers lead to Pauli spin susceptibility growing critically at low electron densities. In the immediate vicinity of the metal-insulator transition (MIT), both the resistance and the effective interactions become temperature dependent and exhibit a fan-like spread as the MIT is crossed. A resistance-interaction flow diagram clearly reveals a quantum critical point.