Dissipation induced by vortex fluctuations in Bi2Sr2CaCu2O8 films: magnetic dependence of the quasi-activation energy

Abstract We present a set of resistivity measurements on different Bi 2 Sr 2 CaCu 2 O 8 films, as a function of temperature and magnetic field, in order to study the dissipation behaviour above the irreversibility line. The dissipation is well described by a phenomenological model for the fluctuative motion of fluxons in a region of phase inhomogeneities. The presence of a maximum of the glasslike activation energy, at about 2 kG is interpreted as 3D-2D crossover induced by the magnetic field.