Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 23: Two-dimensional Materials II: graphene (joint session HL/CPP)
HL 23.1: Vortrag
Dienstag, 2. April 2019, 14:00–14:15, H36
Field-controllable spin relaxation anisotropy in graphene/hBN heterostructures — •Klaus Zollner1, Martin Gmitra2, and Jaroslav Fabian1 — 1Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany — 2Institute of Physics, P. J. Šafárik University in Košice, 04001 Košice, Slovakia
Measurements show a large and tunable anisotropy in the spin relaxation of hBN encapsulated bilayer graphene [1,2], similar to what is observed in graphene/TMDC heterostructures [3]. Combining systematic first principles calculations for graphene/hBN heterostructures with a minimal tight-binding model, we extract spin-orbit coupling parameters of graphene in the µeV range. The extracted model parameters depend on (i) interlayer distances, (ii) stacking configurations, and (iii) an external electric field, resulting in a rich parameter space. Based on the Dyakonov-Perel formalism we calculate spin relaxation times for graphene, in the nanosecond range, in agreement with recent experimental measurements. A very important finding is that the spin relaxation anisotropy is maximum close to the charge neutrality point, decreasing with the doping level. In addition, we also show that the anisotropy can be tuned by means of an external electric field, via the precise control of the Rashba SOC.
This work is supported by the DFG SPP 1666.
[1] Xu et al., PRL 121, 127703 (2018)
[2] Leutenantsmeyer et al., PRL 121, 127702 (2018)
[3] Cummings et al., PRL 119, 206601 (2017)