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FRI: Friday Contributed Sessions

FRI 11: Quantum 2D-Moiré and Rhombohedral van-der-Waals Systems: Contributed Session to Symposium

FRI 11.5: Vortrag

Freitag, 12. September 2025, 11:45–12:00, ZHG104

Electronic Transport in Twisted Bilayer Graphene: Towards Quantum Moiré-tronics — •Thomas Stegmann — Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México

We investigate electronic transport in twisted bilayer graphene (TBLG) at small - though not magic - twist angles. In the first part of the talk, we propose a device in which the direction of the current flow can be steered by the twist between the layers. The observed current steering angle exceeds significantly the twist angle itself and arises over a broad range of experimentally accessible parameters. This behavior is attributed to the trigonal warping of the energy bands beyond the van Hove singularity, induced by the moiré pattern. Since the shape of these bands depends on the valley degree of freedom, the resulting current is partially valley-polarized, highlighting potential applications in valleytronics [1]. In the second part, we report anomalous edge states in TBLG at a twist angle of 1.696^∘. These edge states support electronic transport with conductance values near the conductance quantum and give rise to a nonlocal resistance. Notably, this nonlocal effect is not due to chiral edge transport, but due to the fact that these states are localized only at certain edges of the system, depending on how the nanoribbon has been cut from the bulk [2]. Finally, we discuss briefly how the electronic transport in graphene can be guided along atomically thin current paths through the engineering of Kekulé distortions, offering yet another route toward nanoscale current steering [3].
[1] J. Phys: Mater. 5:024003 (2022)
[2] Phys. Rev. B 110:205432 (2024)
[3] Nano Letters 24:2322 (2024)

Keywords: Electronic transport; Twisted bilayer graphene; Edge state transport; nonlocal resistance; Kekulé distortions