Wafer-scale 30° twisted bilayer graphene epitaxially grown on Cu_0.75Ni_0.25 (111)

Twisted bilayer graphene (TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices. Here we report the synthesis and characterization of 30° TBG naturally grown on Cu_0.75Ni_0.25 (111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy. Compared with other substrates, our TBG with a wafer scale is acquired with a shorter growth time. The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu_0.85Ni_0.15 (111). The signature of moiré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution, possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.