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Description
We investigated the superconducting properties of 200 nm thick Nb-Zr thin films with various Zr concentrations ranging from 0 to 22 at.%. 200 nm thick Nb-Zr thin films were deposited on c-plane sapphire substrates by magnetron sputtering at RT, and the microstructures and superconducting properties of the films were systematically analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and physical property measurement systems (PPMS). XRD and TEM analyses show that the bcc Nb-Zr films are typical (110) textured polycrystalline films with 20-30 nm grain diameter columnar grains. We find that critical temperature (Tc) increases from 8.5 K to 9.9 K with increasing Zr concentration in Nb-Zr thin film from 0 to 15-22 at.% and upper critical field (Hc2) values increase from ~3 T to above 10 T. Current results demonstrate that Nb-Zr thin films have improved Tc and Hc2, which is beneficial for potential application to thin film SRF cavities and quantum device applications.