Enhancement of activation energy in nano diamond doped MgB2 superconductor

Temperature dependence behavior of resistivity for nano diamond doped MgB2 superconductor was measured in different magnetic field 0T <= H <= 8T. Irreversibility (H-irr) is enhanced by nano diamond doping. We reveal that flux-creep activation energy is a nonlinear function of current density U-0 alpha J(c)(-0.2). In order to determine the activation energy of thermally activated flux flow, Arrhenius law has been taken into account. The magnetic field dependence of flux flow activation energy of nano diamond doped MgB2 superconductors was calculated from the slope of the linear part of the Arrhenius plot and found to be decrease corresponding with applied field. Therefore, the critical current density of this sample will need to be enhanced for practical applications. (C) 2010 Elsevier B.V. All rights reserved.