Interfacing the thin films of 3d ferromagnetic metals (FM) with molecular layers induces strong modifications of key and device-relevant magnetic parameters, such as magnetic anisotropy, magnetization etc. This is due to the hybridization of the surface FM d orbitals with the p molecular orbitals, resulting in modifications of the effective Spin-Orbit Coupling and Magneto-Cristalline Anisotropy (MCA). I will present theoretical and experimental evidences that the effects induced by the interfacial hybridization are not only quantitative and cause the collapse of the standard magnetic domain structure, promoting instead the establishment of a new Ferromagnetic-Glass State (FGS).
The experimental part will describe polycrystalline Co films hybridized with fullerenes (C60) and Gallium-quinoline (Gaq3) molecules, all investigated by MOKE, AMR, SQUID and MFM measurements. A significant in-plane magnetic hardening of the cobalt layer will be reported, showing a factor 2 enhancement of the coercivity at room temperature and a colossal enhancement at low temperatures with respect to bare cobalt films. Minor loops characterization by MOKE and SQUID revealed an unusual magnetization dynamics significantly deviating from the Rayleigh law, the latter based on domain wall nucleation and motion.
On the theoretical side I will present DFT calculations and a new correlated random anisotropy phenomenological model, able to account for for detected hardening and for the violation of the Rayleigh law.

​ Plus d'information :https://www.spintec.fr/seminar-ferromagnetic-glass-state-observed-in-thin-cobalt-films-hybridised-with-molecular-layers-collapse-of-the-standard-magnetic-domain-structure/​