Scanning gate experiments: from strongly to weakly invasive probes

TL;DR

This paper investigates the transition from strongly invasive to weakly invasive scanning gate microscopy in a two-dimensional electron gas, using experiments and simulations to identify the perturbative regime where conductance changes reflect unperturbed system properties.

Contribution

It introduces a quantitative analysis of the perturbative regime in scanning gate experiments, linking conductance changes to tip potential strength and disorder effects.

Findings

Conductance change is determined by unperturbed system properties in the perturbative regime.

Characteristic length scale of conductance modulation has a disorder-dependent maximum.

Amplitude modulation of conductance increases linearly with tip potential strength.

Abstract

An open resonator fabricated in a two-dimensional electron gas is used to explore the transition from strongly invasive scanning gate microscopy to the perturbative regime of weak tip-induced potentials. With the help of numerical simulations that faithfully reproduce the main experimental findings, we quantify the extent of the perturbative regime in which the tip-induced conductance change is unambiguously determined by properties of the unperturbed system. The correspondence between the experimental and numerical results is established by analyzing the characteristic length scale and the amplitude modulation of the conductance change. In the perturbative regime, the former is shown to assume a disorder-dependent maximum value, while the latter linearly increases with the strength of a weak tip potential.