Time Evolution of Nickel Bismuth interfaces

The interface between nickel bismuth layers is widely reported to be superconducting and due to the proximity of ferromagnetic and high spin-orbit-coupling layers, it is suggested to host an unconventional p-wave or potentially topologically non-trivial superconducting phase. Such a superconducting state would have relevant applications in the emergent field of superconducting spintronics. In our initial studies on Ni/Bi thin films, we have evidence to suggest that the formation of a NiBi_3 phase is responsible for this superconducting state and that it can form easily even at quite modest temperatures around 100C. The purpose of this experiment is to directly determine whether and how NiBi_3 is forming at the interface and to correlate the changes at the interface as the sample is gently annealed with its superconducting properties.