Tunneling images of a 2D electron system in a quantizing magnetic field

TL;DR

This paper uses a scanning probe technique to visualize the local structure of a 2D electron system in a magnetic field, revealing spatial modulations related to disorder at specific Landau level fillings.

Contribution

It demonstrates the application of Subsurface Charge Accumulation imaging to resolve local electronic structures within a 2DES under magnetic fields.

Findings

Spatial structures appear at integer Landau level fillings.

The structures repeat when changing filling factors from 6 to 7.

Images reflect disorder-induced density modulations.

Abstract

We have applied a scanning probe method, Subsurface Charge Accumulation (SCA) imaging, to resolve the local structure of the interior of a semiconductor two-dimensional electron system (2DES) in a tunneling geometry. Near magnetic fields corresponding to integer Landau level filling, submicron scale spatial structure in the out-of-phase component of the tunneling signal becomes visible. In the images presented here, the structure repeats itself when the filling factor is changed from nu=6 to nu=7. Therefore, we believe the images reflect small modulations in the 2DES density caused by the disorder in the sample.