Spin-Dependent ππ* Gap in Graphene on a Magnetic Substrate

We present a detailed analysis of the electronic properties of graphene/Eu/Ni(111). By using angle- and spin-resolved photoemission spectroscopy and ab initio calculations, we show that the intercalation of Eu in the graphene/Ni(111) interface gives rise to a gapped freestanding dispersion of the ππ* Dirac cones at the K¯ point with an additional lifting of the spin degeneracy due to the mixing of graphene and Eu states. The interaction with the magnetic substrate results in a large spin-dependent gap in the Dirac cones with a topological nature characterized by a large Berry curvature and a spin-polarized Van Hove singularity, whose closeness to the Fermi level gives rise to a polaronic band.Received 1 December 2023Revised 6 March 2024Accepted 21 May 2024DOI:https://doi.org/10.1103/PhysRevLett.132.266401© 2024 American Physical SocietyPhysics Subject Headings (PhySH)