Valley Filtering and Electronic Optics Using Polycrystalline Graphene

V. Hung Nguyen, S. Dechamps, P. Dollfus, and J.-C. Charlier
Phys. Rev. Lett. 117, 247702 – Published 9 December 2016

In this Letter, both the manipulation of valley-polarized currents and the optical-like behaviors of Dirac fermions are theoretically explored in polycrystalline graphene. When strain is applied, the misorientation between two graphene domains separated by a grain boundary can result in a mismatch of their electronic structures. Such a discrepancy manifests itself in a strong breaking of the inversion symmetry, leading to perfect valley polarization in a wide range of transmission directions. In addition, these graphene domains act as different media for electron waves, offering the possibility to modulate and obtain negative refraction indexes.

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  • Received 24 May 2016