Effects of unreacted Mg impurities on the transport properties of MgB2

Preprint

26 June 2002

preprint
Published by arXiv in arXiv

https://doi.org/10.48550/arXiv.cond-mat/0206518

Abstract

We synthesized polycrystalline MgB2 from a stoichiometric mixture of Mg and the 11 B isotope under different conditions. All the samples showed bulk superconductivity with Tc = 38~39 K. The samples containing the least amount of unreacted Mg showed the highest Tc and the sharpest transition width (Delta_Tc). A residual resistivity ratio (RRR) of ~ 5.8, and a magnetoresistance (MR), at 40 K, of 12% were obtained for these samples. Moreover, there was no upturn of resistivity in a low temperature region at 10 Tesla. The samples containing appreciable amounts of unreacted Mg showed quite different behaviors; the values of Delta_Tc, RRR, and MR were much larger. An upturn appeared in resistivity of the samples below about 50 K at 10 T and is thought to be due to the unreacted Mg.

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Version 1, 2002-06-26, ArXiv
Published version: Physica C: Superconductivity and its Applications, 377 (1-2), 21.

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