Influence of configurational changes on the superconducting transition temperature of an amorphous zirconium-nickel alloy

The reversible thermal relaxation found in various amorphous materials has been observed in the glassy metal-metal alloy ${\mathrm{Zr}}_{76}$ ${\mathrm{Ni}}_{24}$. The superconducting transition temperature, $T_c$, can increase reversibly in this alloy with increasing temperature of anneal $T_a$ for $T_a\le 300°$C. At $T_a\ge 300°$C an irreversible decrease in $T_c$ occurs. The effect of plastic deformation on $T_c$ appears to be identical to the effect of heat treatment. It is speculated that high temperatures need not be produced during deformation, but rather that stress fields encourage the same atomic-scale relaxation processes which are active in thermal annealing.