Lima O. F. de; Cardoso C. A.
الوصف:
The first direct measurement of an anisotropic superconducting property in MgB2 was achieved for the bulk nucleation field Hc2, in a sample of aligned crystallites. It was found a ratio gamma(T) = <img id="_x0000_i1026" src="../../../img/revistas/bjp/v33n4/a14img01.gif" align=absbottom>/ <img id="_x0000_i1027" src="../../../img/revistas/bjp/v33n4/a14img02.gif" align=absbottom > or = 1.6 - 1.9, for T varying from 32 K to 26K, between H applied parallel to the ab plane, and along the c direction. The anisotropy of the induced critical current density was evaluated through the Bean model to be <img id="_x0000_i1028" src="../../../img/revistas/bjp/v33n4/a14img03.gif" align=absbottom>/ <img id="_x0000_i1029" src="../../../img/revistas/bjp/v33n4/a14img04.gif" align=absbottom>~ 1.5. We present here a brief review of these studies in connection with current results found in the literature.