Doping Effect and Flux Pinning Mechanism of Nano-SiC Additions in MgB2 Strands

TL;DR

This study systematically investigates how nano-SiC additions affect the superconducting properties of MgB2 strands, revealing enhanced critical current density and flux pinning mechanisms through magnetic and transport measurements.

Contribution

It provides new insights into the flux pinning mechanisms and the effects of nano-SiC doping on MgB2 superconductors, including the identification of additional effective pinning centers.

Findings

Nano-SiC doping enhances critical current density Jc.

Differences between magnetic and transport measurements are due to connectivity effects.

Additional effective pinning centers beyond grain boundaries are suggested.

Abstract

Superconducting MgB2 strands with nanometer-scale SiC additions have been investigated systematically using transport and magnetic measurements. A comparative study of MgB2 strands with different nano-SiC addition levels has shown C-doping-enhanced critical current density Jc through enhancements in the upper critical field, Hc2, and decreased anisotropy. The critical current density and flux pinning force density obtained from magnetic measurements were found to greatly differ from the values obtained through transport measurements, particularly with regards to magnetic field dependence. The differences in magnetic and transport results are largely attributed to connectivity related effects. On the other hand, based on the scaling behavior of flux pinning force, there may be other effective pinning centers in MgB2 strands in addition to grain boundary pinning.