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 Karl Franzens University Graz

Graz University of Technology 

The role of oxygen and oxides in spinterfaces: the case of C60 fullerene on Fe(001)
Associate Professor Alberto Brambilla
Physics Department, Politecnico di Milano (Italy)
17:00 - 18:00 Tuesday 31 January 2017 KFU

Spintronics is a research field devoted to understanding and governing the injection, manipulation and detection of the electron spin in solid materials, namely ferromagnetic metals and inorganic semiconductors. Even if the field is relatively young, it already provided several concepts and devices currently used in technological applications. More recently, several experimental and theoretical investigations suggested that organic materials can achieve comparable, or even enhanced, performances in spin-based devices with respect to conventional materials, and that they can also provide new concepts, leading to the new field of Organic Spintronics. The key role in such systems is played by “spinterfaces”, i.e. interfaces between ferromagnetic materials, that are sources of spin-polarized electrons, and organic layers, which are characterized, in particular, by long lifetimes for spin-polarized electrons. A detailed control over the interface characteristics is therefore of paramount importance to define and, eventually, to tailor physical systems with improved capabilities.
In inorganic spintronics systems, it is well-known that the exploitation of thin and ultra-thin oxides in proximity to ferromagnetic metals (for instance, as tunneling barriers in multilayer junctions) directly influences the magnetic properties of the system, very often with beneficial effects. In this talk, I will discuss how the presence of oxygen and ultra-thin oxides may have an influence on spinterfaces, starting from the state of the art in standard spintronics. I will then focus on the prototypical spinterface between C60 fullerene films and Fe(001). I will present atomic insights, as obtained by Scanning Tunneling Microscopy, on the early stages of formation of C60 films on differently prepared surfaces of Fe(001) substrates, ranging from pristine Fe, to the oxygen-saturated surface, to a two-dimensional magnetic Cr oxide stabilized on top of the Fe layer. Such results will be discussed in terms of the different magnetic coupling developing at the interface, as measured by X-ray Magnetic Circular Dichroism. Finally, the near future persepectives of these studies will be briefly addressed.