Spinterface Formation of Sexithiophene (6T) on Ferromagnetic Surfaces

Interfaces between organic molecules and ferromagnetic (FM) materials play a critical role in a variety of remarkable spin-related effects. In order to employ such spinterfaces in next-generation molecular spintronic devices, it is crucial to characterize and control these spin effects. Here, we report the features of prototypical spinterfaces comprised of sexithiophene (6T) (C24H14S6) deposited on FM metal and FM oxide surfaces. We have investigated the controlled coverage of 6T monolayers on an Fe surface using a variety of advanced characterization techniques and show that adsorption leads to the formation of monodisperse conjugated solid islands. Atomic force microscopy (AFM) results show that a 0.5 ML 6T deposition leads to solid islands, while with an increased thickness of 1.25 ML, the material is deposited in the form of aggregated islands. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) data reveal the orientation and electronic structure of the 6T/Fe system. Comparisons are also made to 6T adsorption on the more inert Fe3O4(001) surface revealing the importance of adsorption geometry, molecular packing, and surface reconstruction in determining spinterfacial electronic structure and associated device performance.