Flexible NbTiN thin films for superconducting electronics

Abstract

We compare the superconducting properties of 100 nm thick NbTiN films grown by reactive sputtering on silicon and flexible commercial polyimide. The samples are fabricated by co-sputtering using Nb and Ti targets at room temperature with a reactive atmosphere of N2 and Ar. The films display a polycrystalline structure and superconducting critical temperatures of 13.2 K on polyimide and 13.4 K on silicon. The analysis of the upper critical field reveals huge values, with extrapolation to zero close to 29 T for films on silicon and 23 T for those on polyimide. A comparison of the superconducting transition applying mechanical deformation is shown. Presenting a higher superconducting gap and upper critical fields above than the commonly used elemental Nb, the development of NbTiN thin films on flexible polyimide appears as a potential material for application in superconducting electronics.