Ferromagnetic coupling of mononuclear Fe centers in a self-assembled   metal-organic network on Au(111)
  The magnetic state and magnetic coupling of individual atoms in nanoscale structures relies on a delicate balance between different interactions with the atomic-scale surrounding. Using scanning tunneling microscopy, we resolve the self-assembled formation of highly ordered bilayer structures of Fe atoms and organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe atoms are encaged in a three-dimensional coordination motif by three T4PT molecules in the surface plane and an additional T4PT unit on top. Within this crystal field, the Fe atoms retain a magnetic ground state with easy-axis anisotropy, as evidenced by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The magnetization curves reveal the existence of ferromagnetic coupling between the Fe centers. 
T. R. Umbach, M. Bernien, C. F. Hermanns, A. Kr\"uger, V. Sessi, I.   Fernandez-Torrente, P. Stoll, J. I. Pascual, K. J. Fra...
cond-mat.mes-hall cond-mat.mtrl-sci