Anisotropic superconductivity of niobium based on its response to nonmagnetic disorder
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- Ames Laboratory, and Iowa State University, Ames, IA (United States)
- Polytechnic University of Turin, Torino (Italy); National Institute for Nuclear Physics Torino (Italy)
- Rigetti Computing, Berkeley, CA (United States)
- Northwestern University, Evanston, IL (United States)
- Louisiana State University, Baton Rouge, LA (United States)
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. Here, we obtain a very close quantitative agreement between the theory and the experiment.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- Italian Ministry of Education, University and Research; USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-07CH11358; AC02-07CH11359
- OSTI ID:
- 1907149
- Report Number(s):
- IS-J 10,966
- Journal Information:
- Physical Review. B, Journal Name: Physical Review. B Journal Issue: 22 Vol. 106; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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