On-surface assembled molecular dimers are reversibly switched between ferromagnetic and antiferromagnetic state by STM manipulation

17 January 2023
Molecular dimers are entities that have their own electronic/magnetic properties that are different from their monomer constituents...

….Whereas STM has been used to study dimers made of bare metal atoms adsorbed on a metal surface, similar studies with molecules are scarce despite their potential interest for applications.  IPCMS researchers present an original method to create Mn-Phthalocyanine dimer (MnPc)2 complexes by on-surface assembly. They demonstrate that the dimer can be switched between an antiferromagnetic (AFM) and a ferromagnetic (FM) state upon a small conformational change controlled by STM manipulation. The two states of the molecular switch are easily identified spectroscopically by their Kondo resonance. Experimental results are fully supported by rigorous and exhaustive ab-initio calculations. These findings provide strong arguments for using magnetic dimers as bi-stable molecular switches and open up new research avenues in spintronics, logics and computing at the molecular scale.

This research was highlighted by the editor as the cover page of  Advanced Physics Research Journal, Vol. 2, No1, Jan. 2023.

Schematics of the conformational change controlled by STM manipulation: reversible switching between the on-top and shifted configurations of the MnPc dimer by means of the STM tip.

Read the article: Advanced Physics Research 2022. https://doi.org/10.1002/apxr.20220000

The spatial distribution of spin density in a) On-top and b) Shifted configuration of the MnPc dimer on Ag(111). The on-top configuration of the MnPc dimer couples antiferromagnetically (AFM) through direct exchange, and switches to the ferromagnetic (FM) coupling through super exchange in the shifted configuration. The red and blue colors are representing the spin-up and spin-down density, respectively. The isosurface value is 0.02 eÅ−3.