Simple and advanced ferromagnet/molecule spinterfaces

Spin-polarized charge transfer between a ferromagnet and a molecule can promote molecular ferromagnetism(1,2) and hybridized interfacial states(3,4). Observations of high spin-polarization of Fermi level states at room temperature(5) designate such interfaces as a very promising candidate toward achieving a highly spin-polarized, nanoscale current source at room temperature, when compared to other solutions such as half-metallic systems and solid-state tunnelling over the past decades. We will discuss three aspects of this research. 1) Does the ferromagnet/molecule interface, also called an organic spinterface, exhibit this high spin-polarization as a generic feature? Spin-polarized photoemission experiments reveal that a high spin-polarization of electronics states at the Fermi level also exist at the simple interface between ferromagnetic cobalt and amorphous carbon(6). Furthermore, this effect is general to an array of ferromagnetic and molecular candidates(7). 2) Integrating molecules with intrinsic properties (e.g. spin crossover molecules) into a spinterface toward enhanced functionality requires lowering the charge transfer onto the molecule(8) while magnetizing it(1,2). We propose to achieve this by utilizing interlayer exchange coupling within a more advanced organic spinterface architecture. We present results at room temperature across the fcc Co(001)/Cu/manganese phthalocyanine (MnPc) system(9). 3) Finally, we discuss how the Co/MnPc spinterface's ferromagnetism stabilizes antiferromagnetic ordering at room temperature onto subsequent molecules away from the spinterface, which in turn can exchange bias the Co layer at low temperature(10). Consequences include tunnelling anisotropic magnetoresistance across a CoPc tunnel barrier(11). This augurs new possibilities to transmit spin information across organic semiconductors using spin flip excitations(12).