Graphene doping to enhance flux pinning and supercurrent carrying ability in magnesium diboride superconductor

TL;DR

This study demonstrates that graphene doping significantly enhances the flux pinning and supercurrent capacity of magnesium diboride superconductors, with optimal doping levels leading to a 30-fold increase in critical current density at low temperatures and high magnetic fields.

Contribution

The paper introduces graphene doping as a novel method to improve flux pinning and supercurrent in MgB2, highlighting the roles of carbon substitution, graphene's 2D structure, and strain effects.

Findings

Optimal doping at 3.7 at% graphene increases Jc(B) by a factor of 30 at 5 K and 10 T.

Graphene doping causes little change in the transition temperature of MgB2.

Strain effects and carbon substitution from graphene are key to flux pinning enhancement.

Abstract

It has been shown that graphene doping is sufficient to lead to an improvement in the critical current density - field performance (Jc(B)), with little change in the transition temperature in MgB2. At 3.7 at% graphene doping of MgB2 an optimal enhancement in Jc(B) was reached by a factor of 30 at 5 K and 10 T, compared to the un-doped sample. The results suggested that effective carbon substitutions by grapheme, 2D nature of grapheme and the strain effect induced by difference thermal coefficient between single grapheme sheet and MgB2 superconductor may play an important role in flux pinning enhancement.