Observation of Single-Spin Dirac Fermions at the Graphene/Ferromagnet Interface

With the discovery and first characterization of graphene, its potential for spintronic applications was recognized immediately. Since then, an active field of research has developed trying to overcome the practical hurdles. One of the most severe challenges is to find appropriate interfaces between graphene and ferromagnetic layers, which are granting efficient injection of spin-polarized electrons. Here, we show that graphene grown under appropriate conditions on Co(0001) demonstrates perfect structural properties and simultaneously exhibits highly spin-polarized charge carriers. The latter was conclusively proven by observation of a single-spin Dirac cone near the Fermi level. This was accomplished experimentally using spin- and angle-resolved photoelectron spectroscopy, and theoretically with density functional calculations. Our results demonstrate that the graphene/Co(0001) system represents an interesting candidate for applications in devices using the spin degree of freedom.The authors acknowledge Saint-Petersburg State University for a research Grants 11.37.634.2013 and 11.50.202.2015, RFBR (Grant 14-02-31150), and BMBF (Grant 05K12OD3). A.G. acknowledges support from the ERC Grant Super2D. M.M.O. and E.V.C acknowledge the financial support of the University of Basque Country UPV/EHU (Grant GIC07-IT-756-13) as well as of the Departamento de Educacion del Gobierno Vasco and the Spanish Ministerio de Ciencia e Innovacion (Grant FIS2010-19609-C02-01). We acknowledge Helmholtz Zentrum Berlin für Materialien und Energie for support within bilateral Russian-German Laboratory program