Laser-Induced Voltages at Room Temperature in YBa 2 Cu 3 O 7 and Pr x Y 1-x Ba 2 Cu 3 O 7 Thin Films

Recent reports on high transient transverse voltages at room temperature in YBa2Cu3O7 and PrxY1−xBa2Cu3O7 thin films grown on SrTiO3 single crystal substrates, with a tilt angle between the [ 001 ] cubic axis and the substrate surface plane, have been interpreted by thermoelectric fields transverse to a laser-induced temperature gradient which are caused by the non-zero off diagonal elements of the Seebeck tensor. We have studied this effect in epitaxially grown Pr- doped, as well as undoped YBa2Cu3O7, thin films and observed for a 2 mm long YBa2Cu3O7 strip exposed to a UV photon fluence of 100 mJ/cm2 signals as large as 30 V. The unexpected high values for the signals and their doping dependence are discussed within the frame of a model based on a thermopile arrangement, the growth induced defect structure and the doping induced modifications of the material properties.