Dirac cones in graphene grown on a half-filled 4d-band transition metal

New opportunities for structural and electronic properties engineering of graphene can be achieved by tuning the interfacial interaction, which is ruled by the interplay between d-band filling and geometry of the support. Here, is demonstrated the growth of graphene, featuring Dirac cones around the Fermi level, on the rectangular (110) surfaces of Rh, a half-filled 4d-band transition metal element. The analysis of the structural properties by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) shows that domains with a con-tinuum of possible graphene-substrate orientations with angular scatter of around 10 degrees coexist in graphene/Rh (110) surfaces. Within each domain, surface structure is characterized by a distinct stripe-like moire ' pattern. The interfacial chemistry analysis, by microprobeX-ray photoelectron spectroscopy (mu-XPS), of all the rotational domains studied, demonstrates the existence of two main levels of interfacial interaction strength, similar to previously reported graphene-metal systems characterized by the absence of Dirac cones around the Fermi level. However, the band structures of these domains probed by micro angle resolved photoelectron spectroscopy (mu-ARPES) present Dirac cones, with Fermi velocities comparable with those previously reported on weakly coupled graphene layers. Both the unique properties of graphene/Rh(110) surfaces and the prospect to obtain novel graphene-metal interfaces through the interplay between d-band filling and geometry, are expected to open new opportunities to study phenomena up to now masked behind the interaction with the substrate.

Automated summary

New opportunities for graphene engineering can be achieved by adjusting interfacial interaction in terms of d-band filling and geometry of the support. Growth of graphene on Rh(110) surfaces shows distinct stripe-like moire patterns and Dirac cones around the Fermi level. The analysis also reveals the existence of two levels of interfacial interaction strength and the presence of Dirac cones in band structures of different rotational domains, indicating potential for novel graphene-metal interfaces.