Dissipation of quantized vortex of high-Tc superconductors investigated by microwave impedance: Novel physics in nano-scale space

Dissipation by the vortex motion in cuprate superconductors was investigated by the microwave surface impedance measurement. We discuss our experimental results, with particular interest in comparison with the quasiparticle scattering time in the vortex core with that in the Meissner state, and in the effect of impurity doping. It was found that the moderately clean core picture was rather generic in the high-Tc cuprate. This means the importance of the Andreev reflection at the core boundary for the dissipation by the vortex motion. We argue that the large dissipation by the motion of vortex core is the manifestation of the novel mechanism characteristic of the moderately clean core.