Modulating the Magnetic Coupling in Paramagnetic Co Nanoparticles Embedded in Tris(8-hydroxyquinoline)aluminum for Spintronics Applications

Tailoring the organic–inorganic heterostructure through nanotechnology and molecular engineering is a promising route to achieve high performances of spintronics. Tris(8-hydroxyquinoline)aluminum (Alq3) with effective electron-transport properties and excellent emitting efficiency as an organic light-emitting diode has been employed as a nonmagnetic layer and integrated with magnetic electrodes to become an effective spin filter in organic spintronics. The device performances are strongly influenced by the interfacial spin polarization at the organic–ferromagnetic heterojunction. We therefore manipulated the magnetic exchange coupling of a hybrid organic–ferromagnetic complex through coevaporation to produce hybrid nanoclusters for modulating the degree of hybridization between Co and Alq3. Paramagnetic Alq3–Co nanoclusters with varied volume ratios of Alq3 to Co were fabricated. The results demonstrate that the extent of hybrid N correlates with the ratio of the deposited amount of Co in three paramagnetic nanocluster thin films. The coercivity (Hc) and magnetic moment of all paramagnetic thin films correlated strongly with the degree of hybridization of Co clusters in the coevaporated complex. Notably, the magnetic moment is maximized with the optimized hybrid structure that expresses efficient spin filtering for molecular/organic spintronics.