School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology , Wuhan, Hubei 430074, China.
Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland , College Park, Maryland 20742-4111, United States.
Nano Lett. 2016 Feb 10;16(2):1173-8. doi: 10.1021/acs.nanolett.5b04473. Epub 2016 Jan 26.
Transport measurements were made to study the superconducting transition of four 6 mm long niobium nanowires with different cross-sectional dimensions. A low-temperature residual resistance tail measured with an excitation current of 5 nA is found in the thinnest wire down to 50 mK or 7.7% of Tc of Nb. The functional form of the residual resistance is consistent with quantum phase slip (QPS) processes. Resistance measured at high bias excitation current switches among many discrete values that are well below the normal state resistance. These discrete resistance values as a function of temperature fall into several parallel curves all showing QPS-like decay in the low temperature limit similar to that found at low current. The coexistence of QPS-like resistance tails and resistance jumps found in the same wire unifies results from previous experiments where these two distinct sets of evidence for QPS are exclusive of each other.
传输测量用于研究四条具有不同横截面尺寸的 6 毫米长铌纳米线的超导转变。在最细的线中，在 50 mK 或铌的 Tc 的 7.7%以下，发现了用 5 nA 的激励电流测量的低温剩余电阻尾部。剩余电阻的函数形式与量子相位滑移 (QPS) 过程一致。在高偏置激励电流下测量的电阻在许多离散值之间切换，这些离散值远低于正常状态电阻。这些离散电阻值随温度的变化分为几个平行的曲线，所有曲线都显示出类似于在低电流下发现的 QPS 样衰减。在同一根线中发现的 QPS 样电阻尾部和电阻跃变的共存，统一了以前实验的结果，其中 QPS 的这两个不同证据彼此排斥。
