Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 80: Graphene

TT 80.7: Vortrag

Donnerstag, 15. März 2018, 11:00–11:15, H 3005

Lifshitz transition and thermoelectric properties of bilayer graphene — Dominik Suszalski, Grzegorz Rut, and •Adam Rycerz — Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland

This is a numerical study of thermoelectric properies of ballistic bilayer graphene in the presence of trigonal warping term in the effective Hamiltonian. We find, in mesoscopic samples of the length exceeding 10 micrometers at sub-Kelvin temperatures, that both the Seebeck coefficient and the Lorentz number show anomalies (the additional maximum and minimum, respectively) when the electrochemical potential is close to the Lifshitz energy, which can be attributed to the presence of the van Hove singularity in a bulk density of states. At higher temperatures the anomalies vanish, but measurable quantities characterizing remaining maximum of the Seebeck coefficient still unveil the presence of massless Dirac fermions. Behavior of the thermoelectric figure of merit (ZT) is also discussed.