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Magnetoresistance, voltage‐current characteristics, and Hall effect measurements of bulk MgB 2 superconductors
Author(s) -
Kayed T. S.
Publication year - 2004
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200310148
Subject(s) - van der pauw method , magnetoresistance , condensed matter physics , superconductivity , hall effect , magnetic field , field (mathematics) , chemistry , materials science , analytical chemistry (journal) , physics , mathematics , chromatography , quantum mechanics , pure mathematics
Bulk MgB 2 samples were prepared from the commercially available powder (Alfa‐Aesar). One of the samples was used in measuring the transport properties by the DC four‐probe technique while the other was used in measuring Hall effect using the van‐der‐Pauw configuration. From the transport measurements, we noticed that the R‐T curves shift to lower temperatures under applied magnetic field without any observed enlargement of the transition width. T c gradually decreases from 37 K at zero field to 32 K at B = 1.4 T. Our V‐I data were found to obey a power law expression V ∝ I β(T, B) . The change of β with temperature and magnetic field was shown and discussed. R H is positive under positive applied magnetic field. The 1/ R H linear dependency on T, usually observed in high temperature superconductors, could not be observed in our case. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)