title: On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors.
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.
authors.affiliation: School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006, Australia. waikong.yeoh@sydney.edu.au.
authors.forename: W K
authors.initials: WK
authors.lastname: Yeoh
authors.forename: X Y
authors.initials: XY
authors.lastname: Cui
authors.forename: B
authors.initials: B
authors.lastname: Gault
authors.forename: K S B
authors.initials: KS
authors.lastname: De Silva
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: H W
authors.initials: HW
authors.lastname: Liu
authors.forename: H-W
authors.initials: HW
authors.lastname: Yen
authors.forename: D
authors.initials: D
authors.lastname: Wong
authors.forename: P
authors.initials: P
authors.lastname: Bao
authors.forename: D J
authors.initials: DJ
authors.lastname: Larson
authors.forename: I
authors.initials: I
authors.lastname: Martin
authors.forename: W X
authors.initials: WX
authors.lastname: Li
authors.forename: R K
authors.initials: RK
authors.lastname: Zheng
authors.forename: X L
authors.initials: XL
authors.lastname: Wang
authors.forename: S X
authors.initials: SX
authors.lastname: Dou
authors.forename: S P
authors.initials: SP
authors.lastname: Ringer