Highly textured niobium films for applications in vortex-electronics

Highly textured Nb-films were grown by electron-beam evaporation on sapphire substrates. The crystalline quality was examined by Rutherford-backscattering-channeling and X-ray diffraction methods. The channeling minimum yield is 2%. On c-plane sapphire the evaluation of rocking curve measurements yielded 99.98% [111] Nb // (0001) sapphire and 0.02% [110] Nb // (0001) sapphire. Measurements on microbridges with widths ranging from 2 mu m to 100 mu m (film thickness 500 nm) showed a residual resistivity ratio (R/sub 295K//R/sub 10K/) of up to 90 and critical current densities at 4.2 K and 0.2 T as low as 1.7*10/sup 4/ A/cm/sup 2/. These Nb-films form the basis for devices for local generation and detection of vortices. The writing and erasure of vortices and their detection by means of an integrated superconducting quantum interference device (SQUID) are demonstrated.<
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