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Present work on superconducting multiband MgB2 was started to sort out some relevant question such as how does the band scattering mechanism behaves with density and type of extrinsic defects, How does the pinning force constant in the intergrain and intragrain regions compare with other low Tc and high Tc superconductors? With the introduction of defects, is there some reflection of the changing scattering mechanism on the rf penetration depth? Ion irradiation was used to create extrinsic defects in MgB2 and we found that band scattering mechanisms can be selectively tuned with the type of extrinsic defects. Study of variation in rf penetration depth shows evidence for very strong intergrain pinning it also reflected the modification in the band scattering. We compare the Bulk pinning force constant, intergrain connectivity and broadening of superconducting transition of MgB2 with Bi2Sr2Ca2Cu3O10 and NbSe2 and analyze the magnetoresistance data for MgB2 in the context of thermally activated flux flow behavior and compare vortex activation energy and provide evidence of Arrhenius behavior in the MgB2 samples. The possibilities & future extension of this work is also presented.

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Author studied the effect of pinning disorder in superconducting MgB2 for doctorate. He joined UGC-DAE-CSR Mumbai Centre as a faculty after Ph.D. from Jawaharlal Nehru University, India. His current research interest is characterizing magnetic & multifunctional materials using temperature & magnetic field dependent neutron diffraction.

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