Flux Pinning in Y- and Ag-Doped MgB₂

Jack Dyson¹, Daniele Rinaldi¹, Gianni Barucca¹, Gianni Albertini^1*, Simone Sprio², Anna Tampieri²

¹SIMAU, Università Politecnica delle Marche, Ancona, Italy.
²Institute of Science and Technology for Ceramics, National Research Council, Faenza, Italy.

DOI: 10.4236/ampc.2015.510043                

Abstract

High temperature superconductor research is presently concentrated upon the flux pinning properties of the Abrikosov lattice of the mixed-mode superconducting phase. The temperature thermal fluctuations, current and magnetic field unpin the flux vortices and so cause electromagnetic resistivity in high temperature superconductors. Materials with higher vortex pinning exhibit less resistivity and are more attractive for industrial uses. In the present article, we measured and correlated the pinning flux energy barrier, determined by AC magnetic measurements, and transmission electron microscopy measurements to the critical current J_c in Yttrium- and Silver-doped MgB₂ superconductors. The energy of the flux vortex was evaluated as a function of the magnetic field. The energy barrier curves suggest an optimal doping level to occur in doped materials. This result only depends on the optimal size and distribution of precipitates, and not on their chemical composition. The energy barriers have been compared with that of undoped MgB₂ in literature.

Keywords

Flux Pinning, AC Magnetic Measurements, Critical Current, Yttrium-Doping, Silver-Doping, MgB₂ Superconductors, Transmission Electron Microscopy, X-Ray Diffraction

Conflicts of Interest

The authors declare no conflicts of interest.

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