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O: Fachverband Oberflächenphysik
O 109: Focus Session: Proximity Effects in Epitaxial Graphene II
O 109.7: Vortrag
Freitag, 22. März 2024, 12:30–12:45, MA 141
Magnetotransport of Bi(110) islands on epitaxial graphene — •Julian Koch1, Sergii Sologub1,2, Chitran Ghosal1, and Christoph Tegenkamp1 — 1Institut für Physik, TU Chemnitz, Reichenhainerstr. 70, 09126 Chemnitz — 2Institute of Physics, NAS of Ukraine, Nauki avenue 46, 03028 Kyiv
Magnetotransport measurements using a 4 T magnet were performed on Bi islands on monolayer graphene/SiC with average thickness up to 3.6 bilayers (BL). They are supported by structural investigations using SPA-LEED and STM, which reveal that Bi predominately grows as needle-like islands with a (110) termination (see also [1]).
The carrier concentration determined from the SdH oscillations remains at 1 × 1013 cm−1 independent of the Bi coverage. In contrast, photoemission spectroscopy shows a strong doping of the graphene by Bi [2], indicating that the carrier concentration is highly anisotropic. This is confirmed by a positive, temperature independent contribution to the magnetoresistivity, which indicates that the Bi covered regions are electrically dead zones causing the electrons to scatter at the boundaries. This reduces the mobility from around 2250 cm2/(Vs) for MLG to 1920 cm2/(Vs) at 2.4 BL Bi, a decrease of approximately 14%. The weak localization of the clean surface is gradually reduced with increasing Bi coverage. This is caused solely by a decrease of the coherence length of the scattered electrons. The scattering lenghts associated with inter- and intravalley scattering remain unchanged.
[1] Koch et al. J. Phys.: Condens. Matter 36, 065701 (2024)
[2] Gierz et al. Nano Lett. 8, 12, 4603 (2008)