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

Abstract

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 singlespin 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.

Interface-Induced Spin Polarization in Graphene on Chromia

“…The effect has been reported for a variety of molecules on ferromagnetic substrates as well as for graphene [Dedkov 2008, Dzemiantsova 2011, Mandal 2014, Marchenko 2015, Weser 2010, Weser 2011, Usachov 2015, also on ferromagnetic substrates. This trend towards an induced polarization in the adlayer may be rationalized in terms of the Stoner criterion [Ma'Mari 2015], and induced polarization from proximity effects is well described by mean field arguments [Dowben 1991, Mathon 1986, Schwenk 1998].…”

Variation of the character of spin-orbit interaction by Pt intercalation underneath graphene on Ir(111)

“…Although graphene due to a small atomic number of carbon atoms has an extremely low value of intrinsic SOI, it was recently shown, that an interaction with the substrate can induce spin-dependent effects in graphene [13][14][15]. Hybridization of the graphene and substrate d states leads to the spin splitting of the Dirac conelike π state, with the value of splitting up to 100 meV.…”

Local electronic properties of the graphene-protected giant Rashba-split BiAg2 surface

“…This property is particularly exciting when graphene is deposited or formed on the surface of a ferromagnet or a material which exhibits strong spin-orbit interaction [13][14][15][16][17][18][19]. Here, interfacial contact between graphene and the respective material might lead to the appearance of different new phenomena in graphene and at the interface, such as induced magnetism in graphene [20][21][22], possible induced spin-orbit splitting of the graphene π states [23,24], conservation of spin-polarized electron emission from the underlying ferromagnetic material [13,15], etc.Previously published works on the adsorption of graphene on the surfaces of heavy materials, such as Ir (111) and Au(111), demonstrate that such contacts only weakly modify the dispersion of the spin-orbit split surface states of the metal surface. Adsorption of graphene merely leads to a rigid shift of the respective surface states to smaller binding energies [16,25,26], which was explained by the stronger localization of the surface state wave function, leading to a corresponding energy shift.…”