Novel spin functionalities of C60 based metallo-molecular interfaces

Novel functionalities of C60-based interfaces are investigated with the aim of controlling induced spin-dependent phenomena through electrical and optical charging in photovoltaic devices and the generation of spin-triplet correlations in magneto-molecular/superconductor proximity systems.

Low-energy muon spin rotation is used to probe local magnetic field distributions in molecule/metal-oxide heterojunctions. It is shown that the population of interfacial traps after electrical and optical charging produces an induced magnetisation due to the spin-splitting of the interface. This is supported by XAS and XMLD measurements in similar systems. The emergence of a peak at 282 eV, often associated with interfacial hybridisation, after an electrical bias shows a magnetic field dependence in its X-ray linear dichroism. We propose how these effects may be reversibly switched on and off through the tuning of the interfacial chemistry via electromigration of oxygen in the device.

In Nb/C60 stacks a superconducting state can be induced in the molecular layer via the proximity effect. The incorporation of weakly magnetic Cu/C60 interfaces leads to the emergence of a paramagnetic spin susceptibility
in the superconducting state, as probed by low-energy muon spin rotation. We attribute this effect to the generation of odd-frequency spin-triplet correlations at the spin-split Cu/C60 interface.

These studies are a demonstration of novel device architectures available to the field of molecular spintronics. Utilising the unique spin-dependent
phenomena observed in hybrid molecular interfaces, systems with new functionalities can be designed.