Magnetic coupling of porphyrin molecules through graphene

TL;DR

This study demonstrates that paramagnetic CoOEP molecules on graphene can have their magnetic moments aligned through antiferromagnetic coupling to a Ni substrate, mediated by graphene's c electronic system, without covalent bonding.

Contribution

It provides experimental and theoretical evidence of magnetic coupling of molecules through graphene mediated by c electrons, advancing organic spin electronics.

Findings

Magnetic moments of CoOEP molecules can be aligned via antiferromagnetic coupling.

Coupling is mediated through graphene's c electronic system.

No covalent bonds are formed between molecules and substrate.

Abstract

Graphene is expected to complement todays Si-based information technology. In particular, magnetic molecules in contact with graphene constitute a tantalizing approach towards organic spin electronics because of the reduced conductivity mismatch at the interface. In such a system a bit is represented by a single molecular magnetic moment, which must be stabilized against thermal fluctuations. Here, we show in a combined experimental and theoretical study that the moments of paramagnetic Co-octaethylporphyrin (CoOEP) molecules on graphene can be aligned by a remarkable antiferromagnetic coupling to a Ni substrate underneath the graphene. This coupling is mediated via the \pi\ electronic system of graphene, while no covalent bonds between the molecule and the substrate are established.