Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 14: Poster: Two-Dimenaional Materials and Topological Insulators

HL 14.10: Poster

Montag, 20. März 2017, 14:00–18:00, P2-OG3

Transport measurements in high mobility hBN-graphene-WS2 stacks — •Tobias Rockinger¹, Tobias Völkl¹, Martin Drienovsky¹, Kenji Watanabe², Takashi Taniguchi², Dieter Weiss¹, and Jonathan Eroms¹ — ¹Institute of Experimental and Applied Physics, University of Regensburg, D-93053 Regensburg — ²National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

To induce spin-orbit coupling in graphene, heterostructures of graphene and tungsten disulfide (WS2) are investigated. To achieve high mobilities, we encapsulated graphene between hexagonal boron nitride (hBN) and WS2 via the van der Waals pickup method. Using Cr/Au edge contacts it is possible to achieve reliable, low resistance contacts. In this way we obtained carrier mobilities in graphene between 30.000  cm²/Vs and 116.000  cm²/Vs. We observed Shubnikov-de Haas oscillations in graphene sandwiched in between WS2 and hBN. While searching for weak localization and weak antilocalization we get results which are dominated by other effects. It seems that due to the small (0,8 µ m) width of the hall bar geometry, propagation of electrons through the structure is mainly influenced by sample edges and ballistic effects. This leads to a peak in the magnetoresistance around 100 mT. With this value we calculated a cyclotron radius of 0,8 µ m and an effective sample width of 0,4 µ m which equates 50 percent of the measured width.