Dr. Christopher Gutierrez, University of British Columbia

"Visualizing a Relativistic Quantum Hall Liquid in a Graphene Quantum Dot"

Abstract: Creating and probing the spatial and magnetic confinement of matter is ubiquitous in physics, from thermonuclear fusion to ultracold atoms. Spatial confinement leads to localized atomic-like states, as seen for example in semiconductor quantum dots (QDs); magnetic confinement leads to electrons performing cyclotron motion and is responsible for the integer quantum Hall effect. But what happens when we finely tune from spatial to magnetic confinement, and what role do electron interactions play?

In this talk I will present the first detailed scanning tunneling microscopy/spectroscopy measurements that directly visualize the evolution from spatial to magnetic confinement in a nanoscale system. Using trapped relativistic massless Dirac fermions in a ‘rewritable’ graphene QD, I will show how the application of a magnetic field causes the atomic shell-like QD states to “condense” into highly degenerate Landau levels. Here, increased electron interactions lead to the subsequent formation of a "wedding cake" structure of compressible-incompressible electron strips, showing that custom-printed QDs are a new platform for corralling quantum Hall liquids.