Two-Gap Superconductivity in Niobium Carbide-Coated Single-Walled Carbon Nanotubes: A First-Principles Study

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• 作者：Deepa Sharma ; Neena Jaggi
• 关键词：Superconductivity ; Proximity effect ; SWCNT ; Niobium carbide ; Density functional theory ; CASTEP ; Material studio
• 刊名：Journal of Superconductivity and Novel Magnetism
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：30
• 期：2
• 页码：371-377
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Strongly Correlated Systems, Superconductivity; Magnetism, Magnetic Materials; Condensed Matter Physics; Characterization and Evaluation of Materials;
• 出版者：Springer US
• ISSN：1557-1947
• 卷排序：30

文摘

Superconductivity in carbon nanotubes is attracting worldwide attention because of the reported high superconducting transition temperature in small-diameter single-walled carbon nanotubes (SWCNTs). However, it is well known that superconductivity in low-dimensional (quasi-1D) systems is not so common due to low density of states (DOS), strong quantum fluctuations and other phenomena in such systems. In this paper, we present theoretical investigations of the proximity effect of superconducting niobium carbide on single-walled carbon nanotube using density functional theory (DFT). The relaxed structure shows that Nb atoms are held around the SWCNT, forming a layer through weak van der Waals’ forces. The stability of the structure has been confirmed by Hirshfeld analysis and Mullikan population analysis as well. The study of the electronic band structure of the pristine and modified SWCNT shows a fascinating condensation of electronic states and a striking shift in the Fermi level. Further, two additional band gaps have appeared below the valence band suggesting some kind of pairing mechanism being operational. This indicates the possibility of superconducting behaviour in SWCNT in proximity of niobium carbide. The relaxed structure thus envisions the feasibility and stability of NbC-coated SWCNTs which will have superconducting properties as well as the remarkable mechanical and optical properties of SWCNTs. This prediction seeks interest of the researchers to try and develop such a novel nanomaterial which, if realized, will prove to be highly significant for many technological applications.