Probing Magnetism in Artificial Metal–Organic Complexes Using Electronic Spin Relaxometry

JUNE 24, 2020

Xue Zhang, Philip Willke, Aparajita Singha, Christoph Wolf, Taner Esat, Minhee Choi, Andreas J. Heinrich, and Taeyoung Choi
Journal of Physical Chemistry Letters 11, 14, 5618–5624 (2020)


The metal-organic interaction has been playing a vital role in engineering spins and fabricating functional magnetic structures. This emphasizes the significance to study how the magnetic properties of metal atoms change under the influence of nearby molecules. In this work, we investigate spin properties and dynamics of single metalloorganic complexes by utilizing electronic spin pump-probe technique to probe and image a spin center within the complex in a scanning tunneling microscope (STM). Our work highlights that the combination of STM with electronic spin relaxometry can provide highly valuable clues for investigating magnetic metal-organic nanostructures.


Single spins are considered as a versatile candidate for miniaturizing information devices down to the nanoscale. To engineer the spin’s properties, metal–organic frameworks provide a promising route which in turn requires thorough understanding of the metal–molecule interaction. Here, we investigate the magnetic robustness of a single iron (Fe) atom in artificially built Fe–tetracyanoethylene (TCNE) complexes by using low-temperature scanning tunneling microscopy (STM). We find that the magnetic anisotropy and spin relaxation dynamics of the Fe atom within the complexes remain unperturbed in comparison to well-isolated Fe atoms. Density functional theory (DFT) calculations support our experimental findings, suggesting that the 3d orbitals of the Fe atom remain largely undisturbed while the 4s and 4p orbitals are rearranged in the process of forming a complex. To precisely determine the location of the spin center within the complex, we utilize STM-based spin relaxometry, mapping out the spatial dependence of spin relaxation with subnanometer resolution. Our work suggests that the magnetic properties of atoms can remain unchanged while being embedded in a weakly bound molecular framework.