Upper critical and irreversible fields of polycrystalline CeFeAsO1-xFx superconductors
Abstract
We have investigated the upper critical (Hc2) and irreversible (Hirr) fields of polycrystalline samples of Ce oxypnictide at different doping levels. Hc2 was obtained from temperature dependent resistivity measurements with increasing applied magnetic field. Critical field values as high as 150 Tesla were observed with a decreasing trend as the doping level shifts from a slightly under-doped state to the highly over-doped region. The irreversible fields were lower in this superconductor compared with other rare-earth oxypnictides, with values below 3 Tesla at 20 K. However, Hirr was found to increase with increasing doping, opposite to that of Hc2. The origin of Hirr was studied by determining the exponent `n' extracted from plots of log10(Hirr) versus log10(1-T/Tc)^n. We found that Hirr follows a 3D vortex lattice-melting model similar to the other low anisotropic iron-based superconductors.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- February 2012
- Bibcode:
- 2012APS..MART22015C