Effects of interactions and disorder 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.