QUASI-PARTICLE VS VORTEX MOTION DISSIPATION IN THE MIXED-STATE OF YBA2CU3O7-DELTA USING A CORBINO DISK SAMPLE GEOMETRY

The mixed state resistive tail of sintered YBa2Cu3O7-delta is Studied using a Corbino disk sample geometry. When the transport current passe s radially from the rim of the disk sample to its center, a two compon ent potential drop signal is detected below T-c. This drop is due to ( i) quasiparticles W-q and (ii) vortex-core-motion related contribution W-phi. When the contact pairs measuring the total drop W are placed r adially, W-q(r) and W-phi(r) are found to follow markedly distinctive r-functional dependences. This provides a unique possibility to deconv olute the relative strengths of both contributions. The results obtain ed suggest that the mixed state dissipation of high-T-c superconductor s is strongly influenced by the quasiparticle excitations in contrast to the case of conventional low critical temperature materials.