Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111)

TL;DR

This study demonstrates the self-assembly of a highly ordered Fe-based metal-organic network on Au(111) with ferromagnetically coupled Fe centers, characterized by advanced microscopy and spectroscopy techniques.

Contribution

It reveals the formation of a novel bilayer Fe-organic network with ferromagnetic coupling on a gold surface, combining structural and magnetic analysis.

Findings

Fe atoms form a self-assembled bilayer structure on Au(111)

Fe centers exhibit a magnetic ground state with easy-axis anisotropy

Ferromagnetic coupling between Fe centers confirmed by magnetization measurements

Abstract

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.