Interfacial antiferromagnetic coupling and high spin polarization in metallic phthalocyanines

This is the authors' abstract. We don't add key points for this paper.

Exploration and understanding of the spinterface between magnetic electrodes and organic semiconductors are vital to get an insight into interfacial science and develop spintronic devices. Intrigued by the fact that the modification of chemical states may affect interfacial exchange coupling, magnetic interactions between a series of metallic phthalocyanines (MPcs, M=Cr, Mn, Fe, Co) and surface oxidized Co were studied. Interestingly, these four MPcs are all antiferromagnetically coupled with the Co substrate via the interfacial O atomic layer, but the coupling strength strongly relies on the type of metallic ion in the MPcs. The physical mechanism for different exchange strengths is explored and discussed in terms of a superexchange model via O atoms. It is also noted that the adsorption energy and work function of the surface oxidized Co were sensitive to the metallic ions of MPcs. The valence and spin state of central $3d$ metallic ions could be tuned by the surface oxidized Co. Very interestingly, high negative spin-polarized spinterfaces are obtained in these MPcs. The spin polarizations are up to {-}86% and {-}80% for CrPc and MnPc, respectively. Additionally, high spin polarization can be maintained beyond room temperature because of the very large interfacial coupling energy, demonstrating a promising application of MPcs in spintronic devices.