title: High critical field NbC superconductor on carbon spheres.
abstract: Niobium carbide (NbC) nanoparticles embedded on the surface of carbon spheres (CS) were synthesized at 1350 °C by the carbothermal reduction of niobium oxide precursor in flowing argon (Nbc@CS). The morphology, crystal structure, and magnetic properties of the hybrid nanocomposite were investigated by means of electron microscopy, X-ray diffraction and a superconducting quantum interference device. It was found that the NbC@CS nanocomposites exhibit type-II superconductivity with a critical temperature (Tc) of 8-12 K, typical for stoichiometric NbC. The superconducting hysteresis loop reveals several interesting traits, including strong vortex pinning, the presence of asymmetry and a high penetration field. Moreover, the sample shows much improved irreversible (Hirr), lower (Hc1) and upper (Hc2) critical fields. The coherence length (ξ), penetration depth (λ), and Ginzburg-Landau (κ) parameters for the sample were estimated to be 9.78 nm, 33 nm and 3.39, respectively.
authors.affiliation: Department of Civil and Chemical Engineering, University of South Africa (UNISA), South Africa. kaustavbhattacharjee@gmail.com.
authors.forename: Kaustav
authors.initials: K
authors.lastname: Bhattacharjee
authors.affiliation: Department of Electronic Engineering, Tohoku University, Sendai 980-0845, Japan.
authors.forename: Satya Prakash
authors.initials: SP
authors.lastname: Pati
authors.affiliation: Department of Civil and Chemical Engineering, University of South Africa (UNISA), South Africa. kaustavbhattacharjee@gmail.com and DST/CSIR National Centre for Nanostructured Materials, Material Science and Manufacturing, Pretoria, South Africa. amaity@csir.co.za.
authors.forename: Arjun
authors.initials: A
authors.lastname: Maity