Dissipative resistivity and activation energy U( T, H) in the textured superconducting MgB 2 bulk

Abstract

The temperature dependence of dissipative resistivity has been measured by the flux transform configuration in applied magnetic field up to 7.5 T perpendicular to the surface of a textured MgB 2 bulk. The temperature dependence of the resistivity follows the Bloch–Gruneisen formula, ρ(T)=ρ 0+A T Θ m∫ 0 Θ/T x m dx (1− e −x)( e x−1) , showing an electron–phonon scattering mechanism. The resistive transition becomes broader with increasing applied field H. The field dependence of the characteristic temperature T th, peak temperature T p and irreversibility temperature T irr shows a good power law, H= H 0(1− T/ T i (0)) n , with n=1.18±0.02 and H 0=37±1 T for H∥ c. The dissipative resistivity for H>1 T can be scaled by the thermally activated flux creep model, ρ= ρ 0exp(− U e/ T) with U e=(1− T/ T p) 2.3exp(14−0.776 H). Moreover, the dynamic of vortices exhibits a strong 3D behavior.