Electronic and magnetic structure of C60/Fe3O4(001): a hybrid interface for organic spintronics

Abstract

We report on the electronic and magnetic characterization of the hybrid interface constituted of C₆₀ molecules and an epitaxial Fe₃O₄(001) surface grown on GaAs(001). Using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD), we demonstrate that a stable C₆₀ sub-monolayer (ML) can be retained on the Fe₃O₄(001) surface upon in situ annealing at 250 °C. A carbon K-edge dichroic signal of 1% with respect to the XAS C 1s → π* peak intensity has been observed, indicative of a weaker electronic interaction of C₆₀ with Fe₃O₄(001) compared to the previously reported case of C₆₀/Fe(001). Remarkably, the Fe L-edge XMCD spectrum of Fe₃O₄(001) reveals a reduced Fe³⁺/Fe²⁺ ratio upon C₆₀ sub-ML adsorption. This observation has been ascribed to electron donation by the C₆₀ molecules, as a consequence of the high work function of Fe₃O₄(001). Our present work underlines the significance of chemical interactions between inorganic magnetic surfaces and molecular adsorbates for tuning of the electronic and magnetic properties of the interfaces, which have a profound impact on spin-polarized charge transport in hybrid organic–inorganic spintronic devices.