Aull, S.; Ebrahimi, O.; Karakas, N.; Knobloch, J.; Kugeler, O.; Treimer, W.: Suppressed Meissner-effect in Niobium: Visualized with polarized neutron radiography. Journal of Physics: Conference Series 340 (2012), p. 012001/1-6
10.1088/1742-6596/340/1/012001
Open Access Version (externer Anbieter)
Abstract:
Low temperature superconductors ideally exhibit the Meissner-effect, i.e. magnetic flux is expelled from the material during superconducting transition. We report about the complete suppression of the Meissner-effect in two differently surface-treated niobium samples by means of polarized neutron radiography. Both samples were studied in the Meissner phase, T < Tc = 9.25[K] with an external magnetic field Bext = 6.3mT and for T < Tc and Bext = 0. Neutron radiographs of both samples were recorded, imaging the depolarization of the neutron spin for T > Tc and Bext = 6.4mT, T < Tc and Bext = 6.3mT, and for T < Tc and Bext = 0. After turning off Bext at a temperature below Tc strong position dependent flux pinning was observed in the untreated sample and more uniform flux pinning in the case of the surface - BCP treatment.