Substrate dependent proximity effect of niobium film

Proximity effect between superconductor (SC) and normal metal (NM) is manifested as the diminished superconductivity in SC film by NM substrate. We have studied the magnetron-sputtered and post-annealed niobium film on two different substrates, stainless steel 316 and OFHC copper ($\rho _{\mathrm{SUS}}$/$\rho_{\mathrm{Cu}}\sim $10$^{\mathrm{2}})$. The research shows that a larger conductivity in NM substrate results in a more strongly suppressed superconductivity of the deposited film. We will also show comparison of other characteristics of the SC films related to the superconductivity with analysis techniques such as AFM (atomic force microscopy), SEM (scanning electron microscopy), XPS (x-ray photoelectron spectroscopy), PPMS (physical property measurement system) and MPMS (magnetic property measurement system).