Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 6: 2D Materials 1 (joint session HL/CPP/DS)
HL 6.7: Vortrag
Montag, 5. September 2022, 11:30–11:45, H36
Counterintuitive electric-field dependence of weak antilocalization in a bilayer graphene/WSe2 heterostructure — Julia Amann1, Tobias Völkl1, Tobias Rockinger1, Denis Kochan2, Kenji Watanabe3, Takashi Taniguchi3, Jaroslav Fabian2, Dieter Weiss1, and •Jonathan Eroms1 — 1Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany — 2Institute of Theoretical Physics, University of Regensburg, Regensburg, Germany — 3National Institute for Materials Science, Tsukuba, Japan
Heterostructures of bilayer graphene (BLG) and transition metal dichalcogenides (TMDC) were recently proposed as a means of generating a gate-tunable, proximity-induced spin-orbit coupling (SOC) in graphene. Total SOC splitting of the band structure increases monotonically with the out-of-plane electric field, as confirmed by recent charge transport experiments. To elucidate the spin relaxation caused by SOC, weak antilocalization (WAL) experiments are frequently employed. Contrary to the naïve expectation of a monotonic increase of the WAL effect strength with electric field D, we observe a maximum of WAL visibility around D=0. This counterintuitive behaviour originates in the intricate dependence of WAL in graphene on two different spin lifetimes τsym and τasy, which are due to spin relaxation caused by the valley-Zeeman and Rashba terms, respectively. Our calculations, based on modeling spin precession by an 8× 8 Hamiltonian of BLG with one-sided TMDC show the same non-monotonic dependence on D as the experimental data.