arXiv subjects

S. V. Kravchenko

Publications and source records attributed to S. V. Kravchenko.

74 records · Page 5Linked to original sources

arXiv1994

Temperature Induced Transitions between Insulator, Metal, and Quantum Hall States

We report the observation of TEMPERATURE-INDUCED transitions between insulator, metal, and quantum-Hall behaviors for transport coefficients in the very dilute high mobility two-dimensional electron system in silicon. We consider the $ν=1$ quantum Hall effect at the border of it's existence, at very low electron density. Our data show that as the temperature decreases, the extended states at $ν=1$ (above the Fermi level at higher temperature so that the system behaves as an insulator) sink below the Fermi energy, so that the quantum Hall effect occurs. As the extended states cross the Fermi level, the conductivity has a temperature dependence characteristic of a metallic system.

cond-mat↗

arXiv1994

Possible Metal/Insulator Transition at B=0 in Two Dimensions

We have studied the zero magnetic field resistivity of unique high- mobility two-dimensional electron system in silicon. At very low electron density (but higher than some sample-dependent critical value, $n_{cr}\sim 10^{11}$ cm$^{-2}$), CONVENTIONAL WEAK LOCALIZATION IS OVERPOWERED BY A SHARP DROP OF RESISTIVITY BY AN ORDER OF MAGNITUDE with decreasing temperature below 1--2 K. No further evidence for electron localization is seen down to at least 20 mK. For $n_s<N_{cr}$, the sample is insulating. The resistivity is empirically found to SCALE WITH TEMPERATURE BOTH BELOW AND ABOVE $n_{cr}$ WITH A SINGLE PARAMETER which approaches zero at $n_s=n_{cr}$ suggesting a metal/ insulator phase transition.

cond-mat↗