We report measurements of entropy transport due to vortex motion in single-cyrstal ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$. From these magnetothermal measurements we are able to determine thermodynamic properties, such as the transport line energy and superconducting phase boundary ${\mathit{T}}_{\mathit{c}}$(H), as well as transport parameters associated with flux motion. Below ${\mathit{T}}_{\mathit{c}}$, the data are compared with the microscopic theory of Caroli and Maki. Interestingly, we also find entropy transport in the fluctuation regime above ${\mathit{T}}_{\mathit{c}}$, which grows with applied field and for which no theory exists.

• Received 12 March 1990

DOI:https://doi.org/10.1103/PhysRevLett.64.3090