4 research outputs found
Colossal infrared and terahertz magneto-optical activity in a two-dimensional Dirac material
When two-dimensional electron gases (2DEGs) are exposed to magnetic field,
they resonantly absorb electromagnetic radiation via electronic transitions
between Landau levels (LLs). In 2DEGs with a Dirac spectrum, such as graphene,
theory predicts an exceptionally high infrared magneto-absorption, even at zero
doping. However, the measured LL magneto-optical effects in graphene have been
much weaker than expected because of imperfections in the samples available so
far for such experiments. Here we measure magneto-transmission and Faraday
rotation in high-mobility encapsulated monolayer graphene using a custom
designed setup for magneto-infrared microspectroscopy. Our results show a
strongly enhanced magneto-optical activity in the infrared and terahertz ranges
characterized by a maximum allowed (50%) absorption of light, a 100% magnetic
circular dichroism as well as a record high Faraday rotation. Considering that
sizeable effects have been already observed at routinely achievable magnetic
fields, our findings demonstrate a new potential of magnetic tuning in 2D Dirac
materials for long-wavelength optoelectronics and plasmonics.Comment: 14 pages, 4 figure
Fabry-Perot enhanced Faraday rotation in graphene
We demonstrate that giant Faraday rotation in graphene in the terahertz range
due to the cyclotron resonance is further increased by constructive Fabry-Perot
interference in the supporting substrate. Simultaneously, an enhanced total
transmission is achieved, making this effect doubly advantageous for
graphene-based magneto-optical applications. As an example, we present
far-infrared spectra of epitaxial multilayer graphene grown on the C-face of
6H-SiC, where the interference fringes are spectrally resolved and a Faraday
rotation up to 0.15 radians (9{\deg}) is attained. Further, we discuss and
compare other ways to increase the Faraday rotation using the principle of an
optical cavity