Imaging disorder-induced scattering centers in quantum Hall incompressible strip

TL;DR

This study uses a scanning gate microscope with non-equilibrium transport to visualize how disorder potential affects the microscopic structure of the incompressible strip in the quantum Hall effect, revealing disorder-induced scattering centers.

Contribution

It introduces a novel imaging technique combining scanning gate microscopy with non-equilibrium transport to visualize disorder effects in the quantum Hall incompressible strip.

Findings

Disorder potential influences the spatial structure of the IC strip.

Scattering centers such as bright, dark, and annular patterns are observed in low-mobility samples.

Resonance tunneling through impurity states facilitates inter-Landau level scattering.

Abstract

While the disorder-induced quantum Hall (QH) effect has been studied previously, the effect ofdisorder potential on microscopic features of the integer QH effect remains unclear, particularly forthe incompressible (IC) strip. In this research, a scanning gate microscope incorporated with thenonequilibrium transport technique is used to image the region of QH IC strip that emerges near thesample edge. It was found that different mobility samples with varying disorder potentials showedthe same spatial dependence of the IC strip on the filling factor ({\nu}). In the low-mobility samplealone, scattering centers such, bright, dark and annular patterns, alternately appear within the IC strip. These observed patterns are ascribed to inter-LL scattering assisted by resonance tunnelingthrough an impurity bound state. It is concluded that disorder-induced scattering can be effectivelydetected using the applied technique in a low-mobility sample.