Metal-Insulator Transition in a Low-Mobility Two-Dimensional Electron System

TL;DR

This study investigates the metal-insulator transition in a low-mobility silicon two-dimensional electron system by tuning disorder and analyzing conductivity scaling, providing evidence for a critical transition point consistent with scaling theory.

Contribution

It demonstrates the emergence of a metallic phase and characterizes the scaling behavior of conductivity near the transition in a low-mobility 2D electron system.

Findings

Observation of metallic phase at low disorder levels

Single-parameter scaling of conductivity near critical density

Linear beta function consistent with interacting scaling theory

Abstract

We have varied the disorder in a two-dimensional electron system in silicon by applying substrate bias. When the disorder becomes sufficiently low, we observe the emergence of the metallic phase, and find evidence for a metal-insulator transition (MIT): the single-parameter scaling of conductivity with temperature near a critical electron density. We obtain the scaling function $\beta$, which determines the length (or temperature) dependence of the conductance. $\beta$ is smooth and monotonic, and linear in the logarithm of the conductance near the MIT, in agreement with the scaling theory for interacting systems.