Faraday rotation in photons passing through graphene

Letter

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Nature Physics
Published online: 7 November 2010 | doi:10.1038/nphys1816

Giant Faraday rotation in single- and multilayer graphene
Iris Crassee1, Julien Levallois1, Andrew L. Walter2,3, Markus Ostler4, Aaron Bostwick3, Eli Rotenberg3, Thomas Seyller4, Dirk van der Marel1 & Alexey B. Kuzmenko1

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Abstract The rotation of the polarization of light after passing a medium in a magnetic field, discovered by Faraday1, is an optical analogue of the Hall effect, which combines sensitivity to the carrier type with access to a broad energy range. Up to now the thinnest structures showing the Faraday rotation were several-nanometre-thick two-dimensional electron gases2. As the rotation angle is proportional to the distance travelled by the light, an intriguing issue is the scale of this effect in two-dimensional atomic crystals or films—the ultimately thin objects in condensed matter physics. Here we demonstrate that a single atomic layer of carbon—graphene—turns the polarization by several degrees in modest magnetic fields. Such a strong rotation is due to the resonances originating from the cyclotron effect in the classical regime and the inter-Landau-level transitions in the quantum regime. Combined with the possibility of ambipolar doping3, this opens pathways to use graphene in fast tunable ultrathin infrared magneto-optical devices.

Supplementary information: The effect of the substrate

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