Laboratory for Integrated Science
Images of the Quantum Hall Liquid
Ray Ashoori

(a) An SPM charging image of a 2DEG in the quantum Hall regime at filling factor í = 0.89. The image shows bright arcs on a dark background over the 10x10m² field of view. (b) At this magnetic field, the positive tip bias induces a bubble of electrons in the next Landau level. A ring of incompressible states at í = 1 separates the interior of the bubble from the bulk. (c) Arcs arise in the image when the ring intersects a "hotspot" in the 2DEG, causing its resistance to drop.