Awana, V. P. S. and Isobe, M. and Singh , K. P. and Takayama-Muromachi, E. (2006) Fluxoid jump coupled high critical current density of nano-Co3O4 doped MgB2. Analog Integrated Circuits and Signal Processing , 19. pp. 551-555. ISSN 0925-1030

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Abstract

Polycrystalline MgB2 samples, with added 0, 2, 4 and 6% nano-Co3O4, synthesized by vacuum ( 10(-5) Torr) annealing at 750 degrees C for two and a half hours each, are found to be nearly single phase with the presence of only a small quantity of Mg/MgO in the pristine sample in addition to the Co2O3 in the doped compounds. All the samples exhibited clear and sharp diamagnetic transitions at around 38 K, in zero-field-cooled (ZFC) magnetic susceptibility measurements with a sizeable signal. The field-cooled (FC) measurements, though having sharp transitions, showed a very small signal, indicating a high level of pinning centres in these samples. Further, some of the doped samples exhibited the paramagnetic Meissner effect (PME) in an applied field of 5 Oe. The critical current density (J(c)), estimated by invoking Bean's model for the pristine compound, increases by nearly an order of magnitude for 2% and 4% nano-Co3O4 doping and then decreases sharply for the 6% sample at nearly all studied temperatures and applied fields. Further, the increased Jc (similar to 10(8) A cm(-2)) is coupled with fluxoid jumps ( T <= 20 K and H <= 1 T). Fluxoid jumps are not seen in the relatively low Jc pristine or 6% sample. This means that the fluxoid jumps are intrinsic only to the high-J(c) samples.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Springer Verlag.
Subjects:	Applied Physics/Condensed Matter Physics
Divisions:	UNSPECIFIED
Depositing User:	Users 27 not found.
Date Deposited:	10 May 2018 12:34
Last Modified:	10 May 2018 12:34
URI:	http://npl.csircentral.net/id/eprint/2481

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