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O: Fachverband Oberflächenphysik

O 34: Focused Session: Epitaxial Graphene IV

O 34.2: Topical Talk

Mittwoch, 25. März 2009, 11:00–11:30, SCH 251

Exotic properties of graphene at interfaces: spin filtering and mass generation — •Jeroen van den Brink — Universiteit Leiden, The Netherlands — Stanford University, USA

We investigate a number of exotic electronic properties of graphene at interfaces by means of ab initio density functional calculations.

First we show that it is possible to generate a mass for the Dirac fermions in graphene by putting it on a hexagonal boron nitride substrate. The breaking of the two-sublattice symmetry causes the opening of band gap of about 53 meV [1]. This gap can greatly improve room temperature pinch-off characteristics of graphene-based field effect transistors [2].

Second we investigate the spin filtering properties of graphite and graphene. Based upon the observations (i) that their in-plane lattice constants match almost perfectly and (ii) that their electronic structures overlap in reciprocal space for one spin direction only, we predict perfect spin filtering for interfaces between graphite and (111) fcc or (0001) hcp Ni or Co [3,4]. The spin filtering is quite insensitive to roughness and disorder.

[1] Giovannetti et al., Phys. Rev. B. 76, 073103 (2007).

[2] Van den Brink, Nature Nanotechnology 2, 199 (2007).

[3] Karpan et al., Phys. Rev. Lett. 99, 176602 (2007).

[4] Karpan et al., Phys. Rev. B. 78, 195419 (2008).