Mechanism of the c-axis dissipation in Bi2Sr2CaCu2O8-x single crystals

Abstract

We have measured resistivities both in the ab-plane and dong the c-axis on Bi2Sr2CaCu2O8-x single crystals in magnetic fields oriented parallel to the c-axis. Both the ab-plane and the c-axis magnetoresistivities at low temperatures are described by the thermally activated flux creep model with the same value of the thermal activation energy, which scales with H-0.3+/-0.1. We also found a narrow temperature region where the ratio of the c-axis to the ab-plane conductivity in the mixed state exhibits a negative slope with temperature, as predicted by the Koshelev model. In this temperature regime, the c-axis dissipation is presumably due to the phase slips between the Cu-O bilayers caused by the diffusive motion of the pancake vortices in different layers.