Thermally activated motion of two-dimensional vortices in Bi2Sr2CaCu2Oy crystals

The magnetic resistance of two single crystals of Bi2Sr2CaCu2Oy was investigated. Measurements were performed in magnetic fields up to 1.6 T with applied current densities between 0.03 A/cm2 and 3.0 A/cm2. The resistivity of the crystals was analyzed in terms of the thermally activated flux flow expression, ϱ=ϱ0U/Texp(-U/T), where T is the temperature. It was found that the activation energy was given by U∝(H sin θ)-α, where α≈13, and that the …