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We discuss pinning properties of MgB2 thin films grown by pulsed-laser deposition (PLD) and by electron-beam (EB) evaporation. Two mechanisms are identified that contribute most effectively to the pinning of vortices in randomly oriented films. The EB process produces low defected crystallites with small grain size providing enhanced pinning at grain boundaries without degradation of Tc. The PLD process produces films with structural disorder on a scale less that the coherence length that further improves pinning, but also depresses Tc.
The magnetoresistivity and critical current density of well characterized Si-nanoparticle doped and undoped Cu-sheathed MgB$_{2}$ tapes have been measured at temperatures $Tgeq 28$ K in magnetic fields $Bleq 0.9$ T. The irreversibility line $B_{irr}(
We have studied structural and superconducting properties of MgB2 thin films doped with carbon during the hybrid physical-chemical vapor deposition process. A carbon-containing metalorganic precursor bis(cyclopentadienyl)magnesium was added to the ca
We report the effect of annealing on the superconductivity of MgB2 thin films as functions of the postannealing temperature in the range from 700 C to 950 C and of the postannealing time in the range from 30 min to 120 min. On annealing at 900 C for
In this paper, we analyze the upper critical field of four MgB2 thin films, with different resistivity (between 5 to 50 mWcm) and critical temperature (between 29.5 to 38.8 K), measured up to 28 Tesla. In the perpendicular direction the critical fiel
The current-voltage (I-V) characteristics of various MgB2 films have been studied at different magnetic fields parallel to c-axis. At fields mu0H between 0 and 5T, vortex liquid-glass transitions were found in the I-V isotherms. Consistently, the I-V