Cyclotron resonance spectroscopy of symmetry broken states in mono- and bilayer graphene

Monday, September 16, 2019 - 4:00pm

Cyclotron resonance—the resonant absorption of light by charge carriers in a strong magnetic field—is widely used to measure the effective band mass of (semi-)conducting materials. This works because the CR absorption by charge carriers in a parabolic dispersion, which is a reasonable description of most materials, is unaffected by inter-particle interactions. An intriguing corollary is that, for instance, in high-mobility GaAs heterostructures when the electronic transport shows remarkably complex behavior in the regime of the fractional quantum Hall effect, there is still only a single cyclotron resonance peak that is qualitatively little different from a low-mobility device. But: in materials with a linear dispersion such as graphene, this proscription against spectroscopy of interactions does not hold. We have built a dedicated infrared magnetospectroscopy setup for exploring the cyclotron resonance of interacting Dirac systems, and will report our progress including an exciting observation of full integer symmetry breaking of the underlying Landau levels in monolayer graphene. We will also show recent measurements in bilayer graphene and discuss plans for ’shining light’ on other correlated electron systems.

Prof. Erik Henriksen - Washington U
Deepak Singh