Origin of the Resistive Transition Broadening for Superconducting Magnesium Diboride

Abstract

The origin of the superconducting transition broadening for the novel superconductor MgB2 is investigated. The dominant role of twodimensional fluctuations and thermally activated flux flow in the vicinity of the critical temperature is found to be responsible for the resistivity of MgB2 near the superconducting transition. The reasons of the observed extraordinary strong magnetic field dependence of the activation energy of the flux motion are discussed.