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.

Comprehensive review on topological superconducting materials and interfaces

“…These materials are found to have a type-II Dirac semimetal like band structure, which has been confirmed through both DFT calculations and ARPES measurements [93][94][95][96][97]. NbC has a NaCl type crystal structure and its superconducting temperature strongly depend on the lattice parameters [98,99] which increases or decreases with stoichiometry of carbon [100]. A powder XRD pattern fitted with F m -3 m space group symmetry is shown in Fig.…”

Superconductivity with Topological Non-trivial Surface States in NbC

“…Other TMCs, such as VC [26] and CrC [26], are also predicted to have nontrivial band topology along with bulk superconductivity, but experimental confirmation of their non-trivial topological behavior is yet to be realized. Among these TMCs, the NbC and TaC show superconductivity in range of 8 to 11K [22][23][24][27][28][29]. Most of the Superconductivity reports of these materials are based on polycrystalline samples, as it is difficult to grow their single crystals.…”