| A systematic and quantitative study of upper critical fields, H{dollar}sb{lcub}rm C2{rcub}{dollar}(T), in disordered bulk alloys with increasing atomic numbers was carried out. They include alloys of Ti-Mo, Ti-Pd, Zr-Mo, Zr-Pd, Zr-Rh, Hf-Mo, and Hf-Ta. A least-squares fitting routine was performed on H{dollar}sb{lcub}rm C2{rcub}{dollar}(T) with the Werthamer, Helfand, Hohenberg, and Maki (WHHM) theory of dirty superconductors. The main findings are: (1) H{dollar}sb{lcub}rm C2{rcub}{dollar}(T) data for all samples are found to fall below or on the curve with infinite spin-orbit scattering rate ({dollar}lambdasb{lcub}rm s.o.{rcub} = infty{dollar}); (2) furthermore, they fit the WHHM theory very well for all the data (3) {dollar}lambdasb{lcub}rm s.o.{rcub}{dollar} ranges from 0.28 to 2.51 for the 3d and 4d alloys; and (4) its value compares well with theoretical estimation using results from band-structure calculations.; The localization effects on H{dollar}sb{lcub}rm C2{rcub}{dollar}(T) were examined by comparing the electronic density of states obtained from specific heat measurements (absence of field-induced delocalization effects) and those derived from fitting critical field data. Measurements on bulk Zr-Ni, Zr-Rh and Hf-Mo alloys gave the first direct confirmation of theoretical predictions on H{dollar}sb{lcub}rm C2{rcub}{dollar}(T) for the weakly localized 3D systems. To further test the localization theories, magnetoresistance was measured on amorphous Lu-Pd and Lu-Ni alloys. In the absence of contributions from spin-splitting interaction (because of the high spin-orbit scattering rate) and superconducting fluctuations, direct comparison of experimental data with three-dimensional (3D) weak localization theory can be made. Our results follow the trend predicted by theory, but are about 20% larger. Interaction effects with a negative screeing parameter can explain both the discrepancy and the order of magnitude of resistivity. We obtain the inelastic scattering time {dollar}approx{dollar} 2 {dollar}times{dollar} 10{dollar}sp{lcub}-10{rcub}{dollar} T{dollar}sp{lcub}-2{rcub}{dollar} s which can be attributed to electron-phonon processes in disordered metals.; We have also investigated a wide compositional range of U-Fe, U-Co, and U-Ni metallic glasses which contain f-electrons. These uranium glasses exhibit unusual resistivity and superconducting behaviors and have very large upper critical field gradients ({dollar}geq{dollar}40 kG/K) at T{dollar}sb{lcub}rm c{rcub}{dollar}, yielding a renormalized density of states as high as 7.2 states/eV-at. |
