To create super-spintronic devices, both superconductivity and ferromagnetic long-range order (where all spins are pointing in the same direction) will both need to be present. However, conventional theories about superconductors requiring pairs of electrons with their spins pointing in opposite directions meant that superconductivity and ferromagnetism were previously thought to not be able to co-exist. Because of this, there are still challenges when applying this design to low power electronics and quantum computing.
Making systems where the magnetic materials and superconductors 'grow' together can have a significant impact on the performance of the superconductor. The superconducting behaviour can also then only be changed by growing new samples with a different composition or structural design. In this study, published in Communications Physics, the researchers designed a carbon-based molecular hybrid that can be added as an extra layer into the system, creating a possible new design for superconducting spintronic devices.
By designing molecular and metal interfaces, the researchers achieved emergent magnetic and superconducting properties coexisting in a single system, despite these properties not being present in the isolated materials. They used a combination of transmission electron microscopy (TEM), polarised neutron and X-ray reflectivity (PNR/XRR), and low-energy-μSR to study their system, which was based on a superconducting film of niobium.
Their results demonstrate that superconducting correlations can be mediated across a molecular layer of C60 molecules in a thin film, thought to be enabled by the hybridisation of the electrons in the C60 molecules. They saw an unconventional superconducting state present in their hybrid metal/ molecule system that could be used for super-spintronics or in coherence and interferometry applications.
In addition, as the interactions between the metal and the molecular layer can be controlled by electrical or optical irradiation, this breaks down the other major barrier to application, as changes could be made to the system without the need to start again and grow new samples.
The full paper can be found online at DOI: 10.1038/s42005-021-00567-7