Anisotropic superconductivity of niobium based on its response to nonmagnetic disorder
Date
2022-12-14
Authors
Tanatar, Makariy A.
Torsello, Daniele
Joshi, Kamal R.
Ghimire, Sunil
Kopas, Cameron J.
Marshall, Jayss
Mutus, Josh Y.
Ghigo, Gianluca
Zarea, Mehdi
Sauls, James A.
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Iowa State University Digital Repository, Ames IA (United States)
Abstract
Niobium is one of the most studied superconductors, both theoretically and experimentally. It is tremendously important for applications, and it has the highest superconducting transition temperature, Tc = 9.32 K, of all pure metals. In addition to power applications in alloys, pure niobium is used for sensitive magnetosensing, radio-frequency cavities, and, more recently, as circuit metallization layers in superconducting qubits. A detailed understanding of its electronic and superconducting structure, especially its normal and superconducting state anisotropies, is crucial for mitigating the loss of quantum coherence in such devices. Recently, a microscopic theory of the anisotropic properties of niobium with the disorder was put forward. To verify theoretical predictions, we studied the effect of disorder produced by 3.5 MeV proton irradiation of thin Nb films grown by the same team and using the same protocols as those used in transmon qubits. By measuring the superconducting transition temperature and upper critical fields, we show a clear suppression of Tc by potential (nonmagnetic) scattering, which is directly related to the anisotropic order parameter. We obtain a very close quantitative agreement between the theory and the experiment.
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IS-J 10966
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article
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This article is published as Tanatar, Makariy A., Daniele Torsello, Kamal R. Joshi, Sunil Ghimire, Cameron J. Kopas, Jayss Marshall, Josh Y. Mutus et al. "Anisotropic superconductivity of niobium based on its response to nonmagnetic disorder." Physical Review B 106, no. 22 (2022): 224511.
DOI: 10.1103/PhysRevB.106.224511.
Copyright 2022 American Physical Society.
Posted with permission.
DOE Contract Number(s): AC02-07CH11359; AC02-07CH11358; 201785KWLE