Studies of anisotropic thermoelectricity in layered oxide materials and time-resolved phonon kinetics

Transient longitudinal voltage pulses occur in the normal state of thin fil m samples of high-temperature superconductors following the absorption of l ight pulses. Our experiments unambiguously confirm that the pulses arise fr om the thermoelectric response of these layered oxide materials to the heat fluxes propagating within the film in the direction orthogonal to the volt age measurement axis. Good agreement is found between the measured voltage characteristics and a macroscopic model based solely on the Seebeck tensor of the material. The temporal behavior of the experimental signal is also d iscussed. (C) 1999 Elsevier Science B.V. All rights reserved.