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TT: Fachverband Tiefe Temperaturen

TT 1: TR: Graphene 1 (jointly with MA, HL, and DY)

TT 1.1: Invited Talk

Monday, March 14, 2011, 10:30–11:00, HSZ 03

Spin-orbit coupling in graphene: single layer, bilayer, trilayer, and graphite — •Jaroslav Fabian — Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany

In graphene at the Fermi level the spin-orbit splitting is about 25 µeV. Our first-principles [1] and tight-binding [2] investigations show that the splitting originates from d orbitals that hybridize with the p_z ones and form the π band. In an external transverse electric field there is an additional splitting of the bands (the Bychkov-Rashba effect). This extrinsic splitting is solely due to the hybridization of the σ and π orbitals, and is about 10 µeV for typical fields of 1 V/nm. In bi- and trilayer graphene, and in graphite, the intrinsic splitting is also due to the d electrons. The extrinsic splitting at K points has the intrinsic value, of 25 µeV; somewhat away from K the splitting saturates to the Bychkov-Rashba value similar to the single layer graphene. This work is supported by the DFG SFB 689.
M. Gmitra, S. Konschuh, C. Ertler, C. Ambrosch-Draxl, and J. Fabian, Band-structure topologies in graphene: spin-orbit coupling effects from first principles, Phys. Rev. B 80, 235431 (2009).
S. Konschuh, M. Gmitra, and J. Fabian, Tight-binding theory of the spin-orbit coupling in graphene, Phys. Rev. B 82, 245412 (2010).
C. Ertler, S. Konschuh, M. Gmitra, and J. Fabian, Electron spin relaxation in graphene: the role of the substrate, Phys. Rev. B(R) 80, 041405 (2009)