CHARACTERIZATION OF THE PYROELECTRIC EFFECT IN YBA2CU3O7-DELTA

Measurements of the pyroelectric effect in single crystals of YBa2Cu3O7-delta are reported as a function of doping, external electric field, and temperature. The pyroelectric response of the material is found to be accurately described theoretically. The sign pyroelectric voltage V(p) can be switched by an external field. Although poling was possible to some extent, a permanent switching of the direction of polarization could not be achieved at room temperature. A sign reversal of V(p) is observed as a result of thermal cycling, presumably due to activated domain rearrangement. The magnitude of the spontaneous polarization P(s) is found to increase with doping in such a way that the product rhoP(s) remains approximately constant, where rho is the resistivity. The origin of the polarization and the role of possible artifacts are discussed.