Memory Effects in Electron Transport in Si Inversion Layers in the Dilute Regime: Individuality versus Universality

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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 Vcool. Different Vcool 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 Vcool. 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/e², the transport and magnetotransport become nearly universal.