Narrowing of d bands of FeCo layers intercalated under graphene

TL;DR

This study investigates how intercalating FeCo layers under graphene on Ir(111) affects the electronic structure, revealing band narrowing, hybridization, and spin-selective effects through experimental and computational analysis.

Contribution

It provides new insights into the electronic and magnetic modifications caused by FeCo intercalation under graphene, combining experimental spectroscopy with density functional theory calculations.

Findings

FeCo layers grow epitaxially on Ir(111)

Graphene exhibits pronounced corrugation after intercalation

Fe 3d spin bands narrow and split due to hybridization

Abstract

We report on the electronic properties of an artificial system obtained by the intercalation of equiatomic FeCo layers under graphene grown on Ir(111). Upon intercalation, the FeCo film grows epitaxially on Ir(111), resulting in a lattice-mismatched system. By performing Density Functional Theory calculations, we show that the intercalated FeCo layer leads to a pronounced corrugation of the graphene film. At the same time, the FeCo intercalated layers induce a clear transition from a nearly undisturbed to a strongly hybridized graphene {\pi}-band, as measured by angle-resolved photoemission spectroscopy. A comparison of experimental results with the computed band structure and the projected density of states unveils a spin-selective hybridization between the {\pi} band of graphene and FeCo-3d states. Our results demonstrate that the reduced dimensionality, as well as the hybridization within the FeCo layers, induce a narrowing and a clear splitting of Fe 3d-up and Fe 3d-down spin bands of the confined FeCo layers with respect to bulk Fe and Co.