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

TL;DR

This study reveals a scaling behavior of resistivity near the metal/insulator transition in a 2D silicon electron system, indicating a true transition at zero magnetic field contrary to traditional scaling theory.

Contribution

It demonstrates a sample-independent scaling of resistivity with a critical density and identifies a true metal/insulator transition at zero magnetic field in 2D silicon systems.

Findings

Resistivity scales with a single parameter T_0 near the transition.

Critical density n_c where T_0 approaches zero.

Identical temperature dependence of resistivity at B=0 and ν=3/2.

Abstract

We have studied the temperature dependence of resistivity, $\rho$, 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 $T_0\propto|n_s-n_c|^\beta$ with $\beta=1.6\pm0.1$ 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 $\nu=3/2$ 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 $\nu=3/2$ 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.