Author/Authors :
Awana، نويسنده , , V.P.S. and Rawat، نويسنده , , Rajeev and Gupta، نويسنده , , Anurag and Isobe، نويسنده , , M. and Singh، نويسنده , , K.P. and Vajpayee، نويسنده , , Arpita and Kishan، نويسنده , , H. and Takayama-Muromachi، نويسنده , , E. and Narlikar، نويسنده , , A.V.، نويسنده ,
Abstract :
We report the phase formation, and present a detailed study of magnetization and resistivity under magnetic field of MgB2 polycrystalline bulk samples prepared by the Fe-tube encapsulated and vacuum (10−5 Torr) annealed (750 ∘C) route. Zero-field-cooled magnetic susceptibility ( χ ZFC ) measurements exhibited a sharp transition to the superconducting state with a sizeable diamagnetic signal at 39 K ( T c ) . The measured magnetization loops of the samples, despite the presence of flux jumps, exhibited a stable current density ( J c ) of around 2.4×105 A/cm2 in up to 2 T (Tesla) field and at temperatures ( T ) up to 10 K. The upper critical field is estimated from resistivity measurements in various fields and shows a typical value of 8 T at 21 K. Further, χ FC measurements at an applied field of 0.1 T reveal a paramagnetic Meissner effect (PME) that is briefly discussed.
