Anomalous Negative Resistance Phenomena in Twisted Superconducting Nanowire Yarns

Abstract

We report unusual absolute negative resistance phenomena in twisted superconducting yarns consisting of niobium-nitride (NbN) nanowires formed on a template of aligned carbon nanotube (CNT) sheets. In the vicinity of the superconducting critical temperature and critical current, the electrical resistance with a standard four-probe configuration exhibits negative values for many wire-shaped twisted yarns. This anomalous behavior at the superconducting transition stage is analyzed using a simplified circuit model, where the charge conduction is determined by the combination between the intra-and internanofiber transports inside the yarn. The superconducting transition of intrafibrillar transport along CNT-templated NbN nanowires was distinguished from that of an interfibrillar one, where the latter exhibits the ensemble property of superconducting weak links among adjacent NbN nanowires. Furthermore, the topological similarity between the sheet of an aligned array of nanowires and the yarn of twisted nanofibrils enables the occurrence of this anomaly. This study indicates that the quantitative network-based approach is effective for the analysis of anomalous charge conduction through nanowire-based anisotropic materials.

Memristor-like behavior and negative resistance in a superconductor/insulator/ferromagnet device with a pinholes-governed interface

“…In a device showing current-controlled negative differential resistance, the voltage across the terminals will decrease when the current through it grows, until some transition current above which the voltage increases. It is known that negative differential resistance can also appear in four-point transport measurements of crossed-wire junctions under some condition of the ratio between the wires resistance and the junction resistance [13], as observed in a twisted superconducting carbon nanotubes yarns [14] and in vanadium nanowires [15].…”

Electrostrictive Effect of Materials under High Pressure Revealed by Electrochemical Impedance Spectroscopy

“…Pressure generated by a diamond anvil cell (DAC) can exceed megabars and induce tremendous changes in the materials properties of structures, optics, magnetics, and electrics. − All of the changes have their own exclusive research methods. For example, pressure-induced structural phase transition has always been studied with synchrotron radiation X-ray diffraction (XRD) , and superconducting transition can be detected with electrical resistance − and magnetic susceptibility measurements. ,, However, electrostriction, which is a basic phenomenon in all insulators or dielectrics to describe electric field/polarization-induced strain, − has hardly been involved in high-pressure studies, especially with DAC. The chief reason is related to DAC sample configuration.…”