Significant improvement of flux pinning and irreversibility field in nano-Carbon doped MgB2 superconductor

TL;DR

This study demonstrates that nano-Carbon doping in MgB2 superconductors significantly enhances flux pinning and the irreversibility field, leading to improved critical current density and magnetic field performance.

Contribution

The paper presents a successful synthesis of nano-Carbon doped MgB2 with improved superconducting parameters, especially flux pinning and irreversibility field, which are notably higher than undoped samples.

Findings

Irreversibility field (Hirr) increased to 13.4 Tesla at 5K for x=0.08.

Critical current density (Jc) increased by a factor of 24 at 10K and 6 Tesla.

Superconducting transition temperature (Tc) decreases slightly but improves at high fields.

Abstract

We report the synthesis and variation of superconductivity parameters such as transition temperature Tc, upper critical field Hc, critical current density Jc, irreversibility field Hirr and flux pinning parameter (Fp) for the MgB2-xCx system with nano-Carbon doping up to x=0.20. Carbon substitutes successfully on boron site and results in significant enhancement of Hirr and Jc(H). Resistivity measurements reveal a continuous decrease in Tc under zero applied field, while the same improves remarkably at higher fields with an increase in nano-C content for MgB2-xCx system. The irreversibility field value (Hirr) is 7.6 & 6.6 Tesla at 5 and 10K respectively for the pristine sample, which is enhanced to 13.4 and 11.0 Tesla for x = .08 sample at same temperatures. Compared to undoped sample, critical current density (Jc) for the x=0.08 nano-Carbon doped sample is increased by a factor of 24 at 10K at 6 Tesla field.