Depth-resolved characterization of Meissner screening breakdown in surface treated niobium.
Edward Thoeng1,2, Md Asaduzzaman3,4, Philipp Kolb3
1TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada. ethoeng@triumf.ca.
Scientific Reports
|September 14, 2024
Summary
Oxygen-doping superconducting niobium surfaces exhibit longer magnetic field screening lengths. This study reveals how screening evolves near the Meissner phase limits, crucial for superconducting radio-frequency applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Superconductivity
Background:
- Superconducting Radio-Frequency (SRF) cavities are crucial for particle accelerators.
- Understanding magnetic field screening in niobium (Nb) is vital for optimizing SRF performance.
- Surface treatments significantly impact superconducting properties.
Purpose of the Study:
- To directly measure magnetic field screening in niobium samples at the Meissner phase limits.
- To compare the screening behavior of baseline and oxygen-doped (O-doping) Nb surfaces.
- To investigate the influence of applied magnetic fields on screening and phase transitions.
Main Methods:
- Utilized Muon-detected Nuclear Magnetic Resonance (μ-NMR) for depth-resolved magnetic field studies.
- Analyzed the first 100 nm of the Nb surface.
- Employed the μ-SRF beamline at TRIUMF for controlled magnetic field application (up to 200 mT).
Main Results:
- Oxygen-doping significantly increased the magnetic field screening length compared to the baseline treatment.
- Screening length near the Meissner phase limit was found to increase with applied magnetic field.
- Observed the transition from the Meissner to the mixed phase, showing evolving screening profiles.
- Confirmed full magnetic flux penetration at the highest applied fields, indicating complete loss of screening.
Conclusions:
- Oxygen-doping is an effective surface treatment for enhancing magnetic field screening in niobium.
- The observed field-dependent screening behavior provides critical insights into the Meissner phase breakdown.
- These findings are directly applicable to improving the performance and understanding the limits of SRF cavities.
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