title: Magnetic coupling of porphyrin molecules through graphene.
abstract: X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT)+U calculations reveal an unexpected antiferromagnetic coupling between physisorbed paramagnetic Co-porphyrin molecules and a Ni surface, separated by a graphene layer. A positive magnetization at the Ni substrate atoms is mediated by graphene and induces a negative one at the Co site, despite only a very small overlap between macrocyclic π and graphene pz -orbitals.
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Christian F
authors.initials: CF
authors.lastname: Hermanns
authors.forename: Kartick
authors.initials: K
authors.lastname: Tarafder
authors.forename: Matthias
authors.initials: M
authors.lastname: Bernien
authors.forename: Alex
authors.initials: A
authors.lastname: Krüger
authors.forename: Yin-Ming
authors.initials: YM
authors.lastname: Chang
authors.forename: Peter M
authors.initials: PM
authors.lastname: Oppeneer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kuch
keywords: X-ray absorption spectroscopy; graphene; magnetic materials; molecular spintronics