arXiv subjects

M. D'Iorio

Publications and source records attributed to M. D'Iorio.

3 recordsLinked to original sources

arXiv1997

Scaling and the Metal-Insulator Transition in Si/SiGe Quantum Wells

The existence of a metal-insulator transition at zero magnetic field in two- dimensional electron systems has recently been confirmed in high mobility Si-MOSFETs. In this work, the temperature dependence of the resistivity of gated Si/SiGe/Si quantum well structures has revealed a similar metal- insulator transition as a function of carrier density at zero magnetic field. We also report evidence for a Coulomb gap in the temperature dependence of the resistivity of the dilute 2D hole gas confined in a SiGe quantum well. In addition, the resistivity in the insulating phase scales with a single parameter, and is sample independent. These results are consistent with the occurrence of a metal-insulator transition at zero magnetic field in SiGe square quantum wells driven by strong hole-hole interactions.

cond-mat.mes-hall↗

arXiv1994

"Scaling of an anomalous metal/insulator transition in a 2D system in silicon at zero magnetic field"

We have studied the temperature dependence of resistivity, $ρ$, for a two-dimensional electron system in silicon at low electron densities, $n_s\sim10^{11}$ cm$^{-2}$, near the metal/insulator transition. The resistivity was empirically found to scale with a single parameter, $T_0$, which approaches zero at some critical electron density, $n_c$, and increases as a power $T_0\propto|n_s-n_c|^β$ with $β=1.6\pm0.1$ both in metallic ($n_s>n_c$) and insulating ($n_s<n_c$) regions. This dependence was found to be sample-independent. We have also studied the diagonal resistivity at Landau level filling factor $ν=3/2$ where the system is known to be in a metallic state at high magnetic field and in an insulating state at low magnetic field. The temperature dependencies of resistivity at $B=0$ and at $ν=3/2$ were found to be identical. These behaviors suggest a true metal/insulator transition in the two dimensional electron system in silicon at $B=0$, in contrast with the well-known scaling theory.

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↗