Wegscheider, Werner

Date:   Thursday, February 11, 2021
Time:   10:00
Place:   scheduled Zoom meeting
Host:    Klaus Ensslin

News from an old material: quantum Hall effect in GaAs/AlGaAs

Werner Wegscheider
ETH Zurich

In this talk I would like to focus on recent advances in the design and growth of GaAs/AlGaAs heterostructures. By inverting our design recipe for highest-quality two-dimensional charge carrier systems, i.e. by first fixing the target carrier density and then optimizing the structural and growth parameters, we were able to push the limit for the energy gap corresponding to the 5/2 fractional quantum Hall effect state. On a different front, employing cavity spectroscopy in the strong coupling regime, allowed us to study scyrmionic excitations in the vicinity of the v=1 quantum Hall ferromagnet. I will also present an application of the recently introduced planar back-gate design by means of local ion implantation prior to molecular beam epitaxial growth. Using this technique, we investigated different bilayer electron systems with varying tunnel coupling strength. Finally, I will show first results on thermoelectricity measurements in quantum Hall Corbino structures which constitute a proof of principle for the applicability of Landau cooling in such devices.