In the first part of my talk I will describe our observation of the quantum Hall effect (QHE) in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10 cm2/Vs and corresponding Ioffe-Regel disorder parameter 1/(kFλ) ~ 500. Our observations with hydrogenated graphene push the limit of disorder where the QHE can still be attained in a strong magnetic field, suggesting that the QHE might be robust to arbitrarily large disorder. The strongly temperature dependent electrical resistance and high thermal resistance of hydrogenated graphene may further find potential applications in thermometry and bolometry.
In the second part of my talk, I will describe our work on non-reciprocal microwave devices with pristine centimeter-scale graphene with a mobility of ~ 1000 cm2/Vs. The microwave frequency classical Hall effect induces Faraday rotation of microwave polarization, which can be applied to essential non-reciprocal devices such as isolators and circulators. By this means, we demonstrate the first voltage tuneable isolator.


Seminar, September 13, 2013, 12:00. Seminar Room
Hosted by Frank Koppens