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The interaction between organic molecules and magnetic layers has been extensively investigated over the past two decades; yet unresolved questions remain, and new phenomena continue to emerge. In particular, the interface formed between magnetic transition metals and organic molecules has recently been shown to have an unexpected impact on the magnetic properties of these systems, thereby stimulating renewed research interest in this field. [1]
Recently our group revealed that for 3d transition metals such as cobalt, the chemisorption of organic molecules on the surface has been shown to induce a transition from a conventional ferromagnetic state to a glass-like magnetic phase. This behavior arises when the random anisotropy induced by molecules on the surface features correlation effects over characteristic lengths comparable to the intrinsic exchange length of the material. It leads to the emergence of a new magnetic phase characterized by the collapse of the conventional domain structure and the emergence of blurred pseudo-domains, intertwined with diffuse and irregular domain walls. [2]
The effects of this non-conventional magnetic phase have been observed macroscopically and point toward interesting application prospects for these hybrid materials. In particular, an extraordinary magnetic hardening and a breakdown of the Rayleigh law in low-field (minor-loop) magnetization reversal have been experimentally observed in cobalt-molecule hybridized systems.
At the same time, at the microscopic scale, the developed glass state allows the stabilization of otherwise forbidden magnetic textures, such as topological vortex-like magnetic configurations, predicted by micromagnetic simulations and subsequently observed experimentally in real samples [2]. A key feature of the observed effects is that they are not confined to the surface but extend several nanometers into the bulk of the material.
The influence of the organic molecular layer is not limited to ferromagnets but also extends to antiferromagnetic systems, where it has been shown to enhance the overall magnetic stability at the macroscopic scale. In these systems, a clear shift in the characteristic temperatures linked to their magnetic order has been observed in the presence of the molecular layers. [3] Importantly, the effects on antiferromagnets are not only limited to static properties but are also visible in their dynamic magnetic behaviour. [4]
The multi-scale nature of the observed phenomena, together with their ability to propagate several nanometers into the magnetic material, opens up important application perspectives; molecular layers can act not only as fine-tuning elements but also as a means to unlock new functionalities in selected classes of magnetic materials.
[1] Cinchetti M., Valentin Dediu et al., "Activating the molecular spinterface." Nature Mater. 16 (5), 507 (2017) DOI: 10.1038/nmat4902
[2] Benini M. et al. "Collapse of the standard ferromagnetic domain structure in hybrid Co/Molecule bilayers." Nat. Commun. 16.1 (2025): 5807. DOI:10.1038/s41467-025-61068-7
[3] Gnoli L. et al. "Enhancement of magnetic stability in antiferromagnetic CoO films by adsorption of organic molecules." ACS Appl. Electron. Mat. 6.5 (2024): 3138-3146. DOI: 10.1021/acsaelm.3c01599
[4] Marino M. et al. "Chemical tuning of magnons in NiO (001) by Fe-phthalocyanine adsorption." Phys. Chem. Chem. Phys. (2025) 27 (12): 6249–6254. DOI: 10.1039/d4cp04547e
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