Unravelling the strong interplay for interfacial magnetic switching in metal-organic-based spintronics

Organic semiconductors are promising building blocks for multifunctional spintronics. The spinterface plays a key role in affecting the magnetic properties of the performance of spin-based devices. Herein, we reveal the strong interfacial interplay affecting the magnetic switching at the interface of the synthetic paramagnetic tris(8-hydroxyquinoline)iron(iii) (Feq₃) layer on the ferromagnetic surface. In combination with synchrotron-based analysis and density functional theory (DFT) calculations, we observed that the robust magnetic interactions of the Co/Feq₃ system were strongly influenced by the interfacial reaction between Co and Feq₃. As the charge transferred from the contacted Co to Feq₃, the central iron was reduced from Fe(iii) to Fe(ii) and hybridized with the 8-hydroxyquinoline, causing spin polarization at the interface. The reduced central Fe(ii) exhibited apparent ferromagnetic ordering after contact with the ferromagnetic Co substrate. With increasing the Feq₃ layer thickness, the central Fe reverted to its original Fe(iii) state, resulting in the disappearance of ferromagnetic ordering. The thickness dependence of the Feq₃ layer on the magnetic response could be used to tune the spinterface properties and thus the interfacial magnetic interplay. These findings reveal the effect of the strong interfacial redox on the spinterface and open up a promising approach for the use of metal-organic materials in oragnic spintronic devices.