Context
Characterization of superconducting samples by measurement of the « Residual Resistivity Ratio » (RRR) (Φ ≤ 0.15 m, h ≤ 1 m, 4.5 K ≤ T ≤ 300 K) and measurement of the first critical field HC1 (Φ ≤ 0.3 m, h ≤ 1.33 m, 2 K ≤ T ≤ 40 K).
Technical means
- Two small cryostats :
- One cryostat (useful dimensions: h = 1.33 m and Φ = 30 cm), with a removable bottom insert, currently used for first critical field HC1 measurements by local magnetometry (B ≤ 150 mT), but adaptable to other experiments,
- One cryostat (useful dimensions: h = 1 m and Φ = 15 cm) used for RRR measurements,
- Nitrogen and helium dewars (T ≥ 1.9 K),
- Precision voltmeters and ammeters, temperature controllers,
- Lock-in amplifier,
- Labview data acquisition system.
Achievements, related projects
LabCaF devices are mainly used in the framework of R&D projects (in the early stages).
For example, they were used for the characterization of nano-composite superconductors in the framework of the EuCard-2 project (measurement of the first critical field HC1 by local magnetometry).
Industrial services were also performed at the LabCaF (in particular on the RRR experiment).
Technical steps, expertise
- Positioning of the sample in the cryostat,
Remark regarding HC1 measurements: some connections (electrical circuit, instrumentation…) can be done under a mounting plate, before placing the removable bottom insert in the cryostat.
- Liquid nitrogen and helium cooling (this stage lasts about 2 days),
- Data acquisition (2-3 hours for RRR measurements, one day for HC1 measurements).
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