Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Focused Session: Epitaxial Graphene IV
O 34.7: Vortrag
Mittwoch, 25. März 2009, 12:30–12:45, SCH 251
Rashba-type effect in the graphene/Ni(111) system (interchanged with O 34.8) — •Yuriy Dedkov1, Mikhail Fonin2, Ulrich Rüdiger2, and Clemens Laubschat3 — 1FHI Berlin — 2Uni Konstanz — 3TU Dresden
A high efficiency spin-FET device requires a long spin relaxation time compared to the mean time of transport through the channel combined with a sufficient difference of the spin rotation angles between two states ("0" and "1") as well as an insensitivity of spin rotation to the carrier energy. Long electronic mean free paths and negligible spin-orbit coupling in the carbon-based systems, i.e., large spin relaxation times, make graphene an ideal material for the observation of nearly ballistic spin transport and thus realization of the spin-FET. Here we report on angle-resolved photoemission studies of the electronic π states of high-quality epitaxial graphene layers on a Ni(111) surface. In this system the electron binding energy of the π states shows a strong dependence on the magnetization reversal of the Ni film. The observed extraordinarily large energy shift up to 225 meV of the graphene-derived π band peak position for opposite magnetization directions is attributed to a manifestation of the Rashba-type interaction between spin-polarized electrons in the π band and the large gradient of the effective electric field at the graphene/Ni interface. Our findings show that an electron spin in the graphene layer can be manipulated in a controlled way and have important implications for graphene based spintronic devices.