Dissipation in quasi-one-dimensional superconducting single-crystalSnnanowires

Electrical transport measurements were made on single-crystal $\mathrm{Sn}$ nanowires to understand the intrinsic dissipation mechanisms of a one-dimensional superconductor. While the resistance of wires of diameter larger than $70\mathrm{nm}$ drops precipitously to zero at $T_c$ near $3.7\mathrm{K}$, a residual resistive tail extending down to low temperature is found for wires with diameters of 20 and $40\mathrm{nm}$. As a function of temperature, the logarithm of the residual resistance appears as two linear sections, one within a few tenths of a degree below $T_c$ and the other extending down to at least $0.47\mathrm{K}$, the minimum temperature of the measurements. The residual resistance is found to be ohmic at all temperatures below $T_c$ of $\mathrm{Sn}$. These findings are suggestive of a thermally activated phase slip process near $T_c$ and quantum fluctuation-induced phase slip process in the low-temperature regime. When the excitation current exceeds a critical value, the voltage-current $\left(V\text{−}I\right)$ characteristics show a series of discrete steps in approaching the normal state.