Proximity Effect through Chiral Molecules in Nb – Graphene-based Devices

The high level of energy dissipation associated with semiconductor integrated-circuit limits the devices operating frequency. In view of these problems, new concepts of computing and data storage must be developed. One such concept combines superconductivity with spintronics. Superconducting spintronics is a new field, and the present concept for devices requires complicated fabrication of epitaxial ferromagnetic-superconductor multilayers. On a single layer level one may use chiral p-wave superconductors. So far, p-wave superconductivity was shown in anisotropic superconductors such as Sr₂RuO₄, in ferromagnetic heavy fermion superconductors or in non-centrosymmetric superconductors. These systems are either complicated to produce or have low T_C and therefore, are far from application.

Our new simple approach for superconducting spintronics, is based on the use of chiral molecules. Compelling evidence has been gained in recent years that electron transfer through chiral molecules is spin selective. Hence, by injecting a current through chiral molecules, we induce a surface topological chiral p-wave order parameter on a conventional Nb s-wave superconductor. The p-wave behavior is indicated by two step zero bias conduction peaks and a split conduction peak, and also by a rise of theintensity of the peaks with the rise of an external magnetic field under H_C1. The device results are consistent with previous tunneling spectra measurements done in our group. Presented results use a simple reproducible molecular junction device applicable for cryogenic spintronics.