Abstract
A combined scanning tunneling microscopy, x-ray photoelectron spectroscopy, angle-resolved photoemission spectroscopy, and density functional theory study of graphene on a Fe–Ir(111) alloy with variable Ir concentration is presented. Starting from an intercalated Fe layer between the graphene and Ir(111) surface we find that graphene–substrate interaction can be fine-tuned by Fe–Ir alloying at the interface. When a critical Ir-concentration close to 0.25 is reached in the Fe layer, the Dirac cone of graphene is largely restored and can thereafter be tuned across the Fermi level by further increasing the Ir content. Indeed, our study reveals an abrupt transition between a chemisorbed phase at small Ir concentrations and a physisorbed phase above the critical concentration. The latter phase is highly reminiscent of the graphene on the clean Ir(111) surface. Furthermore, the transition is accompanied by an inversion of the graphene’s induced magnetization due to the coupling with the Fe atoms from antiferromagnetic when chemisorbed to weakly ferromagnetic in the physisorption regime, with spin polarizations whose magnitude may be tuned with the amount of Fe content.
Highlights
Since the discovery that graphene (Gr), the two dimensional carbon allotrope, can be isolated and incorporated into electronic devices [1] intense research efforts have been triggered
Afterwards, the intercalation of about one monolayer of Fe between Gr and the Ir(111) substrate was achieved by depositing Fe onto the surface at a temperature of about 600 K
The last set of experiments was again performed on samples prepared under nominally the same conditions and characterization was done by low energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES) to directly access the valence band of Gr in contact with the various Fe–Ir interfaces
Summary
Since the discovery that graphene (Gr), the two dimensional carbon allotrope, can be isolated and incorporated into electronic devices [1] intense research efforts have been triggered. In the case of strong interaction, the linear dispersion is either removed or strongly altered due to a substantial hybridization between localized d-states and Gr’s π-bands. Such effect is observed, for example, in Gr on Ni [6, 7], Co [7,8,9,10,11], and Fe [12, 13]. Similar physisorption regimes are found for Gr on Pt [20, 21], Ir [22, 23] or Pd [24], where, despite the weak hybridization with metallic d
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