Dynamic spin-filtering at the Co/Alq3 interface mediated by weakly coupled second layer Alq3 molecules
Nature Communications 7, 12668 (2016)
Dynamic spin-filtering at the Co/Alq3 interface mediated by weakly coupled second layer Alq3 molecules
Spin-injection in organic materials is often determined by the details of the interaction between the organic molecules and the inorganic magnets used as electrodes, the spinterface. Here we demonstrate that spin-injection into organics can be strongly affected by the spin-dynamics of long-living interface states formed by the magnet and weakly physisorbed molecules. We investigate the case of Alq3 on Co and show, by combining two-photon photoemission experiments with electronic structure theory, that the molecules in the second organic layer determine the long-time dynamics of the spin-injection. These molecules form long-living interface states that, when populated by the photo-excited electrons, acquire a spin-lifetime, which is different for the two spin-species. Such spin-dependent lifetime is the result of the dynamical spin-relaxation driven by the interaction with the substrate. Our work paves the way for the design of weakly-coupled spinterfaces with tunable spin-dependent transport properties.