Resistivity anomalies and intrinsic spin-orbit coupling in superconducting thin film solid solutions of Nb${}_{1-x}$U${}_x$ for $0.15<x<0.40$

Abstract

Polycrystalline thin films of ${\mathrm{Nb}}_{1-x}{\mathrm{U}}_x$ solid solutions with $0.15\le x\le 0.40$ were prepared via d.c. magnetron sputtering at ambient conditions. X-ray characterisation of the samples revealed a systematic shift of the (110) Nb Bragg reflection with U concentration, consistent with substitutional replacement of the Nb by U. Superconductivity was observed in all samples below $2$ K. Analysis of the superconducting critical fields revealed a direct scaling of the spin-orbit scattering and transport scattering times, indicating Elliott-Yafet-type spin relaxation in the system. Magnetoresistivity measurements showed a feature in the range $4$ K $\le T\le 30$ K suggesting a possible a complex interplay between electron-electron interaction and localisation physics.

19 pages, 11 figures