Spin-dependent $\pi$$\pi^{\ast}$ gap in graphene on a magnetic substrate

TL;DR

This study investigates how Eu intercalation in graphene on Ni(111) influences its electronic structure, revealing a spin-dependent gap with topological features and potential for spintronic applications.

Contribution

It provides a detailed experimental and theoretical analysis of spin-dependent electronic gaps in graphene on a magnetic substrate, highlighting the role of Eu intercalation.

Findings

Restoration of nearly freestanding Dirac cones after Eu intercalation

Observation of a large spin-dependent gap with topological characteristics

Identification of a spin-polarized van Hove singularity near the Fermi level

Abstract

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 Eu-intercalation of graphene/Ni(111) restores the nearly freestanding dispersion of the $\pi\pi^\ast$ 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.