Spin scattering and spin-polarized hybrid interface states at a metal-organic interface

Spin scattering at the interface formed between metallic Fe and Cu-phthalocyanine molecules is investigated by spin-polarized scanning tunneling spectroscopy and spin-resolved photoemission. The results are interpreted using first-principles electronic structure theory. The combination of experimental and theoretical techniques allows us to shed light on the role of hybrid interface states for the spin scattering. We show that Cu-phthalocyanine acts, via hybrid interface states, as a local spin filter up to room temperature both below and above the Fermi energy, E-F. At the same time, the molecule behaves as a featureless scattering barrier in a region of about 1 eV around E-F. Similar properties are found for both single molecules and self-assembled molecular layers, so that the acquired microscopic knowledge can be transferred to operating devices.