Interfacial ferromagnetism and atomic structures in high-temperature grown Fe3O4/Pt/Fe3O4 epitaxial trilayers

Abstract

Induced Pt ferromagnetism in Fe 3 O 4 / Pt / Fe 3 O 4 epitaxial trilayer films has been investigated by means of X-ray magnetic circular dichroism (XMCD) at the Pt L 3, 2-edges at various temperatures from 300 K to 12 K, including the metal-insulator transition temperature of Fe 3 O 4 (T V ∼ 114 K). At all the temperatures, we observed clear XMCD signals due to Pt ferromagnetism, the amplitude of which was determined to be 0.39 μ B at 300 K and 0.52 μ B at 12 K for the sample with the Pt thickness of ∼ 2 nm. Interestingly, these values are comparable to or even greater than those in Pt/3 d-ferromagnetic-metal (Fe, Ni, Co, and Ni 81 Fe 19) junction systems. The results can be interpreted in terms of a possible Fe interdiffusion into the Pt layer and also possible Fe-Pt alloying due to its high-temperature deposition.