Memory Effects in Electron Transport in Si Inversion Layers in the   Dilute Regime: Individuality versus Universality
  In order to separate the universal and sample-specific effects in the conductivity of high-mobility Si inversion layers, we studied the electron transport in the same device after cooling it down to 4K at different fixed values of the gate voltage V^{cool}. Different V^{cool} did not modify significantly either the momentum relaxation rate or the strength of electron-electron interactions. However, the temperature dependences of the resistance and the magnetoresistance in parallel magnetic fields, measured in the vicinity of the metal-insulator transition in 2D, carry a strong imprint of individuality of the quenched disorder determined by V^{cool}. This demonstrates that the observed transition between ``metallic'' and insulating regimes involves both, universal effects of electron-electron interaction and sample-specific effects. Far away from the transition, at lower carrier densities and lower resistivities < 0.1 h/e^2, the transport and magnetotransport become nearly universal. 
V. M. Pudalov, M. E. Gershenson, and H. Kojima