Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films

David Klar,Marco Affronte,Kurt Kummer,Valdis Corradini,Mario Ruben,Loic Joly,Heiko Wende,Valentina De Renzi,Roberto Biagi,Bernhard Krumme,Svetlana Klyatskaya,Umberto Del Pennino,Jean-Paul Kappler,Philippe Ohresser,Andrea Candini

doi:10.3762/bjnano.4.36

Abstract

The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100) substrate, to an in situ deposited submonolayer of TbPc2 molecules. Because of the element specificity of the X-ray absorption spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film. On both substrates the TbPc2 molecules couple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface.

Highlights

Molecular spintronic devices as building blocks for future applications in information technology may be a big improvement and lead to higher efficiency [1,2,3,4,5,6,7,8,9]
While most of the well-known Single-molecule magnets (SMMs) consist of several interacting metal ions [10,11,12,13], bis(phthalocyaninato) terbium(III) (TbPc2) has only one rare-earth ion, coordinated by two organic phthalocyanine ligands consisting of nitrogen, carbon and hydrogen atoms (Figure 1a)
By X-ray absorption spectroscopy and X-ray magnetic circular dichroism we study the electronic and magnetic properties of a submonolayer coverage of TbPc2 molecules on ultrathin Co and Ni films, focusing on the magnetic coupling between the substrate and the molecules

Summary

Introduction

Molecular spintronic devices as building blocks for future applications in information technology may be a big improvement and lead to higher efficiency [1,2,3,4,5,6,7,8,9]. Mnand Fe-porphyrin molecules were successfully coupled to ferromagnetic thin films, leading to the alignment of the magnetic moments of the metal ions parallel to the film [15,16,17] or antiparallel due to an interlayer of oxygen [18,19]. It was shown that TbPc2 molecules can be magnetically coupled to a ferromagnetic Ni substrate [20].

Results

Conclusion