Significant enhancement of irreversibility field in clean-limit bulk MgB[sub 2]

Braccini, V.; Cooley, L. D.; Patnaik, S.; Larbalestier, D. C.; Manfrinetti, P.; Palenzona, A.; Siri, A. S.
December 2002
Applied Physics Letters;12/9/2002, Vol. 81 Issue 24, p4577
Academic Journal
Low resistivity MgB[sub 2] bulk samples annealed in Mg vapor show an increase in irreversibility field [sub ·0]H[sup *](T) by a factor of ∼2 in both transport and magnetic measurements. The best sample displayed a magnetic irreversibility field [sub µ0]0H[sup *, sub M]>14 T at 4.2 K and ∼6 T at 20 K. These changes were accompanied by an increase of the 40 K resistivity from 1 to 18 µΩ cm and a lowering of the resistivity ratio from 15 to 3, while the critical temperature T[sub c] decreased by only 1-2 K. These results show that systematic processing changes can make MgB[sub 2] attractive for magnet applications.


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