Long-range magnetic ordering of FePc molecules driven by interfacial coupling with antiferromagnetic Cr2O3

Interfaces between molecular layers and ferromagnetic materials, named spinterfaces, have been widely studied on account of the intriguing magnetic phenomena associated with the spin-polarized hybrid interface states, and of possible innovative applications. This work starts exploring the opportunities given by coupling molecular layers and antiferromagnetic materials, focusing on the magnetoelectric antiferromagnetic insulator Cr2O3. Antiferromagnets are currently of great interest for the future development of spintronics and magnonics applications, since they are stable against external fields and they show dynamic behaviors at much higher frequencies, compared to ferromagnets. On the other hand, interacting with the magnetic structure of an antiferromagnet is more challenging. A possible approach is that of establishing an antiferromagnetic spinterface, in such a way that external stimuli acting on the molecular side can influence the substrate magnetic parameters. Self-assembled monolayers of FePc (iron phthalocyanine) are prepared on thin Cr2O3 films, and the morphological, structural, electronic, and magnetic properties of the resulting antiferromagnetic spinterface are experimentally and theoretically investigated. We observe flat-lying molecular layers that develop a long-range magnetic ordering of the magnetic moments associated with Fe ions. Our calculations support the conclusion that such ordering is established through the interaction at the interface between FePc and Cr2O3.