TRANSPORT ENTROPY OF VORTEX MOTION IN YBA2CU3O7

We report measurements of entropy transport due to vortex motion in single-cyrstal YBa2Cu3O7. From these magnetothermal measurements we are able to determine thermodynamic properties, such as the transport line energy and superconducting phase boundary Tc(H), as well as transport parameters associated with flux motion. Below Tc, the data are compared with the microscopic theory of Caroli and Maki. Interestingly, we also find entropy transport in the fluctuation regime above Tc, which grows with applied field and for which no theory exists. © 1990 The American Physical Society.