Direct observation of micron-scale ordered structure in a two-dimensional electron system

TL;DR

This study uses a novel scanning probe technique to directly observe micron-scale ordered structures in a two-dimensional electron system, revealing unexpected density modulations induced by magnetic fields near specific Landau levels.

Contribution

It provides the first direct imaging of stripe-like density modulations at micron scales in a 2D electron system under magnetic fields, challenging existing theories.

Findings

Stripe-like structures emerge near six and four filled Landau levels.

Density modulations are not static and vary with magnetic field.

Characteristic wavelength of modulations is approximately 2 microns.

Abstract

We have applied a novel scanned probe method to directly resolve the interior structure of a GaAs/AlGaAs two-dimensional electron system in a tunneling geometry. We find that the application of a perpendicular magnetic field can induce surprising density modulations that are not static as a function of the field. Near six and four filled Landau levels, stripe-like structures emerge with a characteristic wave length ~2 microns. Present theories do not account for ordered density modulations on this length scale.