Quantum 2025 – wissenschaftliches Programm
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FRI: Friday Contributed Sessions
FRI 11: Quantum 2D-Moiré and Rhombohedral van-der-Waals Systems: Contributed Session to Symposium
FRI 11.3: Vortrag
Freitag, 12. September 2025, 11:15–11:30, ZHG104
Thermoelectric Transport Measurements in Dual-Gated Bernal Bilayer Graphene — •Moritz Knaak1, Martin Statz1, Kenji Watanabe2, Takashi Taniguchi3, and Thomas Weitz1 — 11. Institute of Physics, Faculty of Physics, University of Göttingen, Göttingen, Germany — 2Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan — 3International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
In dual-gated, hexagonal boron-nitride(hBN) encapsulated Bernal bilayer graphene(BLG) devices a cascade of correlated phases have been identified by magnetoconductance measurements. The correlated phases emerge close to Lifshitz-transitions. There, the density of states(DOS) is high and the kinetic energy gets quenched. While conductance measurements alone can be used to study correlated phases, it is difficult to precisely connect the DOS with said phases. The Seebeck coefficient, extracted from thermoelectric transport measurements provides a more direct probe of the DOS. It is defined as the ratio of the thermal voltage to its inducing temperature difference. We demonstrate measurements of the Seebeck coefficient at 4 K up to a calibration factor. For the measurements we employed an on-chip heater next to an hBN-encapsulated BLG device with graphite contacts and dual graphite gates to simultaneously tune the Fermi-level and an out-of-plane electric field. The source-drain contacts were simultaneously used as quasi-4-point-probe on-chip resistance thermometers to determine the local temperature differences between them.
Keywords: Bernal Bilayer Graphene; Seebeck Coefficient; Thermoelectrics; Lifshitz-Transitions