Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.36: Poster

Mittwoch, 20. März 2024, 18:00–20:30, Poster E

Realizing thermoelectric transport measurements in dual-gated Bernal bilayer graphene — •Moritz Knaak, Martin Statz, and Thomas Weitz — University of Göttingen, Faculty of Physics, 1st Institute of Physics, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

In dual-gated, hexagonal boron nitride (hBN) encapsulated, trigonally warped Bernal bilayer graphene (BLG) many correlated phases at high out-of-plane electric fields have been found.[1-3]. They were found close to Lifshitz transitions, where the density of states(DoS) is high and which can be induced by tuning the out-of plane electric field or the charge carrier density. While conductance measurements alone only give an indirect probe of the DoS, in thermoelectric transport measurements we can study the Seebeck coefficient, which provides a more direct probe of it. To measure the Seebeck coefficient, we use an on-chip heater next to the hBN-encapsulated BLG which is dual-gated and contacted by graphite gates and contacts. The source-drain contacts are simultaneously used as 4-point-probe on-chip resistance thermometers to determine the local temperature differences. A dry-transfer method, e-beam-lithography, reactive ion etching as well as thermal evaporation of contact leads are employed for the fabrication of the thermoelectric devices.

[1] Seiler, A.M. et al. Nature 608, 298-302 (2022) [2] Zhou, H. et al. Science 375, 774-778 (2022) [3] de la Barrera, S. C. et al. Nat. Phys. 18, 771-775 (2022)

Keywords: Bilayer graphene; Thermoelectric transport; Seebeck coefficient