Weak links and phase slip centers in superconducting MgB2 wires

TL;DR

This study investigates the physical structure and electrical properties of MgB2 superconducting wires, revealing the presence of weak links and phase slip centers that affect their superconducting behavior.

Contribution

It provides a detailed analysis of weak links and phase slip centers in MgB2 wires, linking their formation to structural features and their impact on superconducting properties.

Findings

Presence of weak links causes staircase V-I response near critical temperature

Weak links are related to structural features observed in microscopy

Phase slip centers influence the superconducting performance

Abstract

MgB2 superconducting wires were produced by the Mg diffusion method. Scanning electron microscopy (SEM), optical microscopy, dispersive x-ray analysis (EDS) and XRD diffraction were used to study the physical structure and content of the wires. Magnetic properties (Tcm, Hc1, Hc2, Jc by the Bean model) were obtained with a SQUID magnetometer, and transport properties (Tcr, Hc2, resistivity and residual resistivity ratio) were measured using a standard four-lead configuration. The V-I characteristics of the wires close to the critical temperature showed a staircase response, which was attributed to the presence of weak links, creating phase slip centers. The origin of those weak links is discussed in relation to their formation and structure.