Publication Date:
2015-11-04
Description:
Nature Physics 11, 925 (2015). doi:10.1038/nphys3460 Authors: Gil-Ho Lee, Geon-Hyoung Park & Hu-Jong Lee Half a century ago, Veselago proposed ‘left-handed’ materials with negative permittivity and permeability, in which waves propagate with phase and group velocities in opposite directions. Significant work has been undertaken to attain this left-handed response, such as establishing a negative refractive index in so-called metamaterials, which consist of periodic sub-wavelength structures. However, an electronic counterpart has not been demonstrated owing to difficulties in creating repeated structures smaller than the electronic Fermi wavelength of the order ∼10 nm. Here, without needing to engineer sub-wavelength structures, we demonstrate negative refractive behaviour of Dirac fermions in graphene, exploiting its unique relativistic band structure. Analysis of both electron focusing through an n–p–n flat lens and negative refraction across n–p junctions confirms left-handed behaviour in the electronic system. This approach to electronic optics is of particular relevance to the on-going efforts to develop novel quantum devices with emerging layered materials.
Print ISSN:
1745-2473
Electronic ISSN:
1745-2481
Topics:
Physics
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