Low-temperature electronic transport properties of W, Mo, Ta, and Zr thin films

Thin films of the refractory metals W, Mo, and Ta and the metal Zr were deposited upon glass substrates by use of a vacuum arc chamber. The electronic transport properties including magnetoconductance and resistance versus temperature were measured in the temperature regime between 2 and 30 K and in perpendicular magnetic fields up to 7 T. At liquid-helium temperatures, the W, Mo, and Zr films exhibited superconducting fluctuations in the resistance. The W and Mo films had superconducting zero-resistance temperature transitions at 2.75 K, while the Zr film had an estimated transition temperature near 1 K. In contrast, the Ta film exhibited weak localization and electron-electron interaction effects at liquid-helium temperatures with a logarithmic increase in its resistance at decreasing temperatures. Values for the inelastic scattering times were obtained from the magnetoconductance measurements. All of the films had strong spin-orbit scattering.