Abstract :
In the present work, the iron oxypnictide superconductor of the namely Nd0.8Ba0.2FeAsO0.6F0.4 is prepared with respect to the observation of distinct magnetization characteristics arising from both electron and hole doping. A magnetothermal phase diagram is given for the present iron oxypnictide system, based on the irreversibility fields ( H i r r ) and the upper critical fields ( H c 2 ) obtained from magnetotransport measurements, as well as the lower critical fields ( H c 1 ) evaluated by magnetization loops at various temperatures. High H c 2 ( 0 ) are revealed at low temperature range, which is in consistent with the observations of comparatively high critical current ( J c ) and the temperature dependent peak effect in the J c vs H curves.
