Mechanism of Thermally Activatedc-Axis Dissipation in Layered High-TcSuperconductors at High Fields

We propose a simple model which explains experimental behavior of $c$-axis resistivity in layered high- $T_c$ superconductors at high fields in a limited temperature range. It is generally accepted that the in-plane dissipation at low temperatures is caused by a small concentration of mobile pancake vortices whose diffusive motion is thermally activated. We demonstrate that in such a situation a finite conductivity appears also in the $c$ direction due to the phase slips between the planes caused by the mobile pancakes. The model gives a universal relation between the components of conductivity which is in good agreement with experimental data.