Quantum-Classical Crossover and Apparent Metal-Insulator Transition in a   Weakly Interacting 2D Fermi Liquid
  We report the observation of a parallel magnetic field induced metal-insulator transition (MIT) in a high-mobility two-dimensional electron gas (2DEG) for which spin and localization physics most likely play no major role. The high-mobility metallic phase at low field is consistent with the established Fermi liquid transport theory including phonon scattering, whereas the insulating phase at higher field shows a large negative temperature dependence at resistances much smaller than the quantum of resistance, $h/e^2$. We argue that this observation is a direct manifestation of a quantum-classical crossover arising predominantly from the magneto-orbital coupling between the finite width of the 2DEG and the in-plane magnetic field. 
Xiaoqing Zhou, B. Schmidt, C. Proust, G. Gervais, L.N. Pfeiffer, K. W.   West, and S. Das Sarma
cond-mat.mes-hall