From the optoelectronic relay to the artificial synapse, spintronics conceptually encodes and processes information thanks to the two spin states of the electron. Until now, spintronics has mainly focused on the design and operation of efficient discrete electronic components. Yet, it is also important to transmit the encoded information over the mesoscopic distances that separate these spintronic devices. This requires a robust and versatile source of spin-polarized current. Among the various solutions that have been explored these past 25 years (half-metals, dilute magnetic semiconductors, symmetry filtering systems), the recent research track of interfaces between ferromagnetic metals and phthalocyanine molecules seems promising.
But does this require a particular class of molecules such as phthalocyanines ? Researchers at the l’Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS1) have discovered that the strong spin asymmetry of the interface’s electronic states at the Fermi level at room temperature can also occur when an atomic layer of amorphous carbon is deposited on top of the ferromagnetic surface of cobalt. This discovery was made through measurements of spin-polarized photoemission at beamline Cassiopee of Synchrotron Soleil. Within a project financed by the Institut Carnot MICA (2014-2016), a collaboration with researchers from the Institut de Science des Matériaux de Mulhouse (IS2M2) then helped clarify the electronic origin of this remarkable state of matter at the interface.