Inducing Single Spin-polarized Flat Bands in Monolayer Graphene.

Due to the fundamental and technological implications in driving the appearance of non-trivial, exotic topological spin textures and emerging symmetry-broken phases, flat electronic bands in 2D materials, including graphene, are a hot topic in the field of spintronics. Here, via europium doping, we generate single-spin polarized bands in monolayer graphene supported by Co(0001) surface. The doping is controlled by Eu positioning, allowing for the formation of a K-valley localized single spin-polarized low-dispersive parabolic band close to Fermi energy when Eu is on top and a π* flat band with single spin character when Eu is intercalated underneath graphene. In the latter case, Eu also induces a bandgap opening at the Dirac point while the Eu 4f states act as a spin filter, splitting the π band into two spin-polarized branches. The generation of flat bands with single-spin character, as revealed by our spin- and angle-resolved photoemission spectroscopy experiments, complemented by DFT calculations, opens up new pathways towards the realization of spintronic devices exploiting such novel exotic electronic and magnetic states. This article is protected by copyright. All rights reserved.