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arXiv · 1901.02225

A corner reflector of graphene Dirac fermions as a phonon-scattering sensor

H. Graef·Q. Wilmart·M. Rosticher·D. Mele·L. Banszerus·C. Stampfer·T. Taniguchi·K. Watanabe·J-M. Berroir·E. Bocquillon·G. Fève·E. H. T. Teo·B. Plaçais
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Abstract

Dirac fermion optics exploits the refraction of chiral fermions across optics-inspired Klein-tunneling barriers defined by high-transparency p-n junctions. We consider the corner reflector (CR) geometry introduced in optics or radars. We fabricate Dirac fermion CRs using bottom-gate-defined barriers in hBN-encapsulated graphene. By suppressing transmission upon multiple internal reflections, CRs are sensitive to minute phonon scattering rates. We report on doping-independent CR transmission in quantitative agreement with a simple scattering model including thermal phonon scattering. As a new signature of CRs, we observe Fabry-P\'erot oscillations at low temperature, consistent with single-path reflections. Finally, we demonstrate high-frequency operation which promotes CRs as fast phonon detectors. Our work establishes the relevance of Dirac fermion optics in graphene and opens a route for its implementation in topological Dirac matter.

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H. Graef, Q. Wilmart, M. Rosticher, D. Mele, L. Banszerus, C. Stampfer, T. Taniguchi, K. Watanabe, J-M. Berroir, E. Bocquillon, G. Fève, E. H. T. Teo, B. Plaçais. 2019-01-08. A corner reflector of graphene Dirac fermions as a phonon-scattering sensor. https://doi.org/10.1038/s41467-019-10326-6

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