Resistance noise scaling in a 2D system in GaAs

TL;DR

This study investigates 1/f resistance noise in a 2D hole system in GaAs, revealing a scaling behavior near a transition point that suggests a second order or percolation transition.

Contribution

It provides the first detailed analysis of resistance noise scaling in a 2D GaAs system across the metal-insulator transition, indicating a possible critical transition.

Findings

Noise magnitude scales as R^2.4

Noise increases as hole density decreases

Conductivity behavior suggests a critical density below the MIT

Abstract

The 1/f resistance noise of a two-dimensional (2D) hole system in a high mobility GaAs quantum well has been measured on both sides of the 2D metal-insulator transition (MIT) at zero magnetic field (B=0), and deep in the insulating regime. The two measurement methods used are described: I or V fixed, and measurement of resp. V or I fluctuations. The normalized noise magnitude SR/R^2 increases strongly when the hole density is decreased, and its temperature (T) dependence goes from a slight increase with T at the largest densities, to a strong decrease at low density. We find that the noise magnitude scales with the resistance, SR /R^2 ~ R^2.4. Such a scaling is expected for a second order phase transition or a percolation transition. The possible presence of such a transition is investigated by studying the dependence of the conductivity as a function of the density. This dependence is consistent with a critical behavior close to a critical density p* lower than the usual MIT critical density pc.