Amorphous superconducting lanthanum-gold alloys obtained by liquid quenching

Abstract

Results of x-ray diffraction, electrical resistivity, and critical magnetic field measurements are presented for amorphous superconducting lanthanum-gold alloys obtained by liquid quenching. The transition temperature of the alloys is \ensuremath{\sim} 3.5\ifmmode^\circ\else\textdegree\fi{}K. The bulk nature of the samples along with the stability of the amorphous phase at room temperature make this an ideal system for the study of superconductivity in the amorphous state. Estimates of intrinsic parameters including the coherence length $\ensuremath{\xi}$ and penetration depth $\ensuremath{\lambda}$ are presented and discussed. The observed linearity of ${H}_{c2}(T)$ and its extrapolated low-temperature limiting value are discussed and compared to predicted behavior for ${H}_{c2}(T)$.