Graphene-mediated exchange coupling between cobaltocene and magnetic substrates

TL;DR

This study uses first-principles calculations to show how graphene mediates and tunes exchange coupling between a magnetic molecule and a magnetic substrate, revealing mechanisms for spin communication and control.

Contribution

It demonstrates the tunability of exchange coupling via graphene and intercalated magnetic layers, providing insights into molecular spintronics interfaces.

Findings

Exchange coupling is antiferromagnetic and varies with geometry.

Graphene acts as an electronic decoupling layer while enabling spin communication.

Intercalation of magnetic monolayers tunes the coupling strength.

Abstract

Using first-principles calculations we demonstrate sizable exchange coupling between a magnetic molecule and a magnetic substrate via a graphene layer. As a model system we consider cobaltocene (CoCp$_2$) adsorbed on graphene deposited on Ni(111). We find that the magnetic coupling between the molecule and the substrate is antiferromagnetic and varies considerably depending on the molecule structure, the adsorption geometry, and the stacking of graphene on Ni(111). We show how this coupling can be tuned by intercalating a magnetic monolayer, e.g. Fe or Co, between graphene and Ni(111). We identify the leading mechanism responsible for the coupling to be the spatial and energy matching of the frontier orbitals of CoCp$_2$ and graphene close to the Fermi level, and we demonstrate the role of graphene as an electronic decoupling layer, yet allowing spin communication between molecule and substrate.