Effect of disorder on superconductivity of NbN thin films studied using x-ray absorption spectroscopy
| Autor: | Akhil Tayal, Mukul Gupta, Rajeev Rawat, Jens Birch, Shailesh Kalal, Sanjay K. Nayak |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Superconductivity
X-ray absorption spectroscopy Materials science Niobium nitride Condensed matter physics Absorption spectroscopy 02 engineering and technology Electronic structure 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure 01 natural sciences chemistry.chemical_compound chemistry 0103 physical sciences General Materials Science ddc:530 Crystallite Thin film 010306 general physics 0210 nano-technology |
| Zdroj: | Journal of physics / Condensed matter 33(30), 305401 (2021). doi:10.1088/1361-648X/ac00dc Journal of physics / Condensed matter 33(30), 305401-(2021). doi:10.1088/1361-648X/ac00dc |
| ISSN: | 1361-648X |
| DOI: | 10.3204/pubdb-2022-08124 |
| Popis: | Journal of physics / Condensed matter 33(30), 305401 - (2021). doi:10.1088/1361-648X/ac00dc The superconducting transition temperature (T$_C$) of rock-salt type niobium nitride ($δ$ − NbN) typically varies between 9 to 17 K and the theoretically predicted value of 18 K has not been achieved hitherto. The low T$_C$ in $δ$ − NbN has been assigned to some structural disorder which is always present irrespective of the microstructure (polycrystalline or epitaxial), methods or conditions adopted during the growth of NbN thin films. In this work, we investigate the atomic origin of such suppression of the T$_C$ in $δ$ − NbN thin films by employing combined methods of experiments and ab initio simulations. Sputtered $δ$ − NbN thin films with different disorder were studied using the synchrotron-based N and Nb K-edge x-ray absorption spectroscopy techniques. A strong correlation between the superconductivity and the electronic structure reconstruction was observed. The theoretical analysis revealed that under N-rich growth conditions, atomic and molecular N-interstitial defects assisted by cation vacancies form spontaneously and results into a smeared electronic structure around Fermi-level. The role of electronic smearing on the T$_C$ is thoroughly discussed. Published by IOP Publ., Bristol |
| Databáze: | OpenAIRE |
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