Quantum corrections to Boltzmann conductivity in (Cu,Ni)-Zr-Al amorphous alloys

Very high-resolution electrical resistivity data have been presented for Zr-rich (Cu0.36Zr0.64)(1-x)Al-x and (Ni0.5Zr0.5)(1-x)Al-x (0 less than or equal to x less than or equal to 0.2) non-magnetic transition-metal-based amorphous metallic glasses in the temperature range of 1.2-300 K. All the alloys are found to fall into the strong-scattering regime (rho(300) > 165 mu Omega.cm) with negative temperature coefficient of resistance even till 300 K. With the addition of Al in both the systems, the value rho(300) increases because of the enhancement of the degree of disorder. In the low-temperature range, they show a tendency towards superconductivity with transition temperature T-c < 4.2K and large superconducting fluctuations. They are found to be extreme type-II dirty BCS superconductors. A quantitative analysis of the electrical resistivity, based on the electron-electron interaction and localization effects, is reported here in the temperature range, Tc < T < 300K. Pie find, in each specimen, three distinct regions, hitherto only theoretically predicted where the conductivity varies in a sequence of root T, T and root T at low, intermediate and high temperatures, respectively. The only earlier similar observation was made in a ferromagnetic system where the interpretation in terms of quantum interference effects will always remain controversial. A number of parameters, namely, the coefficients of the root T term at low temperatures, diffusion constant, density of states at the Fermi level, inelastic mean free path and relaxation time, estimated from this quantum correction analysis, are in excellent agreement with those from earlier experiments on other amorphous systems.