Coexistence of classical snake states and Aharonov-Bohm oscillations along graphene p−n junctions

Makk, Péter and Handschin, Clevin and Tóvári, Endre and Watanabe, Kenji and Taniguchi, Takashi and Richter, Klaus and Liu, Ming-Hao and Schönenberger, Christian (2018) Coexistence of classical snake states and Aharonov-Bohm oscillations along graphene p−n junctions. PHYSICAL REVIEW B, 98 (3). pp. 1-12. ISSN 2469-9950

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Abstract

Here we present measurements on p − n junctions in encapsulated graphene revealing several sets of magnetoconductance oscillations originating from quasiclassical snake states and edge state Aharonov-Bohm interferences. Even though some of these oscillations have already been observed in suspended and encapsulated devices including different geometries, their identification remained challenging as they were observed in separate measurements, and only a limited amount of data was available. Moreover, these effects have similar experimental signatures, therefore for their proper assignment their simultaneous observation and their detailed characterization is needed. The investigation of the charge carrier density, magnetic field, temperature, and bias dependence of the oscillations enabled us to properly identify their origin. Surprisingly we have found that snake states and Aharonov-Bohm interferences can coexist within a limited parameter range. We explain this using a unified picture of magneto-oscillations and confirm our findings using tight binding simulations. Since p − n junctions are the most important building blocks of graphene based electron-optical elements and edge state interferometers, our findings will be crucial for the design and understanding of future devices.

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