Magnetic flux creep properties in Bi 2Sr 2CaCu 2O 8 films made by the laser evaporation method

Abstract

We measured the temperature dependence of resistivity, ρ( T ), of Bi 2 Sr 2 CaCu 2 O 8 thin films in magnetic fields. These films with a preferential orientation of the c -axis perpendicular to a surface of the substrate show an anisotropy of ρ( T ) versus T curves depending on the field direction and an Arrhenius type dependence, ρ( T )=ρ 0 exp(− U(T, H)/T ). Using the activation energy U(H, T) deduced from the flux creep model, log ρ( T ) versus U(H, T)/T plots are calculated. In low ρ( T ) region the Arrhenius type formula can well explain the ρ( T ) versus T curve, but the magnetic field dependence of U(T, H) is rather different from that expected from the conventional magnetic flux creep model.