Vacancy-induced interfacial ferromagnetic features in SmFeO-filled graphitic carbon foam.

We report a novel structural and magnetic investigation of carbon foam (CFM) materials filled with SmFeO crystals produced by (1) high temperature fusion between SmO- and FeC-filled carbon onions and (2) annealing of iron filled CFM with nanosized SmO. Presence of a defect-rich monolayer-like CFM arrangement characterized by sharp interfaces with a SmFeO single-crystal phase is demonstrated through TEM and HRTEM. Further, the presence of intense sp-rich features with variable carbonate content is evidenced by XPS and Raman spectroscopy. Complementary VSM, SQUID and ESR show also presence of intrinsic magnetization features which appeared to be attributable to the interfacial vacancy-rich regions of the graphitic CFM layers, as confirmed by Raman spectroscopy. Together with these signals, possible ferromagnetic contributions from the SmFeO phase and α-Fe impurities are reported. These observations highlight therefore the presence of switchable interfacial magnetization features at the carbon/SmFeO interface due to the variable concentrations of vacancies at the CFM interface, opening new directions towards applications in magnetic and interfacial-driven ferroelectric devices.