Quantum and superconducting fluctuations effects in disordered Nb_(1-x)Ta_x thin films above T_c

摘要

Disordered Nb_(1-x)Ta_x thin films are prepared with e-gun coevaporation. The influence of the #beta#-phase of tantalum in the critical temperature T_c is observed as a function of the substrate temperature. The measurements of transverse magnetoresistance at various isothermals are interpreted in terms of weak-localization and superconducting fluctuations. From the fitting procedure, the phase breaking rate #tau#_#PHI#~(-1) and the Larkin parameter #beta#_L are estimated as a function of temperature. Conclusions about the dominant inelastic scattering mechanisms at various temperature regions as well as for the dominant mechanism of superconducting fluctuations near the transition temperature are extracted.