Physical Properties At Low Temperature And Superconductivity Of The Zr-based Bulk Metallic Glasses

In this paper, we report the results of electrical-resistivity, low temperature specific heat, superconductivity and critical magnetic field measurements for the Zr-based bulk metallic glasses (BMGs) and its corresponding crystallized sample. Electrical-resistivity measurements between 0.45 K and 300 K were performed on the Zr41Ti14Cu12.5Ni10Be22.5 BMG before and after annealing. The as-prepared metallic glassy sample exhibits negative temperature coefficient of the resistivity in temperature range from 4.2 K to 300 K. The negative temperature coefficient of the resistivity of the as-prepared metallic glassy sample can be reasonably understood with the extended Ziman-Faber theory in terms of the diffraction model for metallic glasses if it is assumed that Zr, Ti, Cu, Ni and Be contribute 1.5, 1.5, 0.5, 0.5 and 2 conduction electrons, respectively. The of the Zr41Ti14Cu12.5Ni10Be22.5 BMG over the temperature range from 4.2 K to 300 K was analyzed by fitting it to a polynomial using a least-squares procedure. The low temperature specific heat of Zr41Ti14Cu12.5Ni10Be22.5 alloys in amorphous and crystallized states was investigated. The amorphous state of the alloy shows much larger specific heat than that of the crystallized state. The density of states near the Fermi level and Debye temperatures, of the alloys are determined. It is found that the density of states at the Fermi level for the amorphous state is higher than that for crystallized state. A much smaller value of in the amorphous state is expected from the soften transverse phonons compared to its corresponding crystallized state.The Zr41Ti14Cu12.5Ni10Be22.5 samples investigated here are superconducting and belong to the typical type-Ⅱ superconductors with a high Ginzburg-Landau parameter. The superconducting critical temperature Tc is 1.62K for the as-prepared amorphous sample and 3.57K for the crystallized sample at zero magnetic field, respectively. The temperature gradient (-dHc2/dT)Tc of the upper critical field Hc2 near critical temperature Tc of the amorphous sample is 2.26T/K. Crystallization of the metallic glass leads to a decrease of (-dHc2/dT)Tc to 1.21T/K. Some superconducting properties of the Zr41Ti14Cu12.5Ni10Be22.5 BMG are gained based on the electrical resistivity and critical field measurements. Estimates of intrinsic parameters including the coherence length and penetration depth are determined and discussed. An analysis of the electron-phonon coupling constant as determined from Tc indicates that the Zr41Ti14Cu12.5Ni10Be22.5 BMG is a weak-coupling superconductor with ≈0.49. The observed linearity of Hc2(t) and its extrapolated low-temperature limiting value are discussed and compared to predicted behavior for Hc2(t).