Interfacial reactivity of magnetic exchange coupled Co/α-Fe2O3(0 0 0 1) interfaces

The present study focuses on the growth mode and interface reactivity of the prototypical Co/α-Fe2O3(0 0 0 1) ferromagnet/antiferromagnet interface. The knowledge of these properties is essential to improve our understanding of the exchange bias phenomenon. The chemical composition of the interface has been determined by means of X-ray absorption spectroscopy and the morphology of the growing Co film by scanning tunneling microscopy. Our experiments evidence a 3D growth and the presence of a spatially limited reactive interface that spreads to approximately one atomic layer on either side of the interface. This area is chemically composed by a layer of reduced hematite and a layer of oxidized cobalt. In the early stages of growth the interface composition is found to be dependent on the Co coverage and reaches quickly a steady state of fixed composition.