On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors

TL;DR

This study demonstrates that doping MgB2 superconductors with graphene oxide significantly enhances supercurrent capacity through atomic doping and texturing, with advanced microscopy and simulations revealing the underlying mechanisms.

Contribution

It introduces a novel experimental approach combining microscopy and simulations to understand how GO doping improves MgB2 superconductors.

Findings

Order of magnitude supercurrent enhancement at 5 K/8 T and 20 K/4 T

Localized atomic doping and texturing improve flux pinning

Methodology applicable to other nanostructure composites

Abstract

Due to their graphene-like properties after oxygen reduction, incorporation of graphene oxide (GO) sheets into correlated-electron materials offers a new pathway for tailoring their properties. Fabricating GO nanocomposites with polycrystalline MgB2 superconductors leads to an order of magnitude enhancement of the supercurrent at 5 K/8 T and 20 K/4 T. Herein, we introduce a novel experimental approach to overcome the formidable challenge of performing quantitative microscopy and microanalysis of such composites, so as to unveil how GO doping influences the structure and hence the material properties. Atom probe microscopy and electron microscopy were used to directly image the GO within the MgB2, and we combined these data with computational simulations to derive the property-enhancing mechanisms. Our results reveal synergetic effects of GO, namely, via localized atomic (carbon and oxygen) doping as well as texturing of the crystals, which provide both inter and intra granular flux pinning. This study opens up new insights into how low-dimensional nanostructures can be integrated into composites to modify the overall properties, using a methodology amenable to a wide range of applications.