Spinterface effects in hybrid La$_{0.7}$Sr$_{0.3}$MnO$_3$ /SrTiO$_3$ /C$_{60}$ /Co magnetic tunnel junctions

International audienceThe orbital hybridization at the Co/C$_{60}$ interface has proved to strongly enhance the magnetic anisotropy of the cobalt layer, promoting such hybrid systems as appealing components for sensing and memory devices. Correspondingly, the same hybridization induces substantial variations in the ability of Co/C$_{60}$ interface to support spin polarized currents and can bring out spin filtering effect. The knowledge of the effects at both sides shall allow for a better and more complete understanding of interfacial physics. In this paper we investigate the Co/C$_{60}$ bilayer in the role of spin polarized electrode in the La$_{0.7}$Sr$_{0.3}$MnO$_3$ /SrTiO$_3$ /C$_{60}$ /Co configuration, thus substituting the bare Co electrode in the well-known La$_{0.7}$Sr$_{0.3}$MnO$_3$ /SrTiO$_3$ /C$_{60}$ /Co magnetic tunnel junction. The study revealed that the spin polarization (SP) of the tunneling currents escaping from the Co/C 60 electrode is generally negative, i.e. inverted with respect to the expected SP of the Co electrode. The observed sign of the spin polarization was confirmed via DFT calculations by considering the hybridization between cobalt and molecular orbitals