Effect of cobalt intercalation on the electronic structure of graphene on Ir(111): Sublattice and time-reversal symmetry breaking
Phys. Rev. B 114, 105401 – Published 3 August, 2026
DOI: https://doi.org/10.1103/8tv2-jw2h
Abstract
Proximity effects between graphene and hybrid ferromagnetic and heavy metal structures offer a promising road for modifying graphene's electronic properties. Such systems have been proposed for spintronic applications due to their perpendicular magnetic anisotropy and significant Dzyaloshinskii-Moriya interaction. Here, we present experimental and theoretical study on electronic and magnetic properties of graphene intercalated by cobalt on Ir(111) single crystal. We have synthesized well-oriented graphene without rotational domains on a Co/Ir(111) system and analyzed the influence of the Co film thickness and the mutual arrangement of C and Co atoms on magnetism and spin-orbit coupling effects. We find that two types of graphene/[3 ML Co]/Ir(111) structures can be realized, exhibiting tilted (TMS) and nontilted (NTMS) magnetic configurations. For the TMS structure, spin-resolved ARPES measurements and density functional theory calculations reveal complex spin structure, consisting predominantly of an in-plane component with a smaller out-of-plane contribution. In contrast, the NTMS structure exhibited spin polarization dominated by the component, indicating out-of-plane magnetization. Our results demonstrate ferrimagnetic ordering of the carbon atoms' magnetic moments along with a tilt of the Co atoms' magnetic moments relative to the surface normal in the graphene/Co/Ir(111) system. Moreover, spin-orbit coupling and exchange interaction lead to valley-dependent widths of local band gaps and differences in the spin splitting of the hybridized C and Co states at the and points. These interactions play a crucial role in the formation of the observed electronic structure in graphene/Co/Ir(111).
