Giant laser-induced voltages at room temperature in Pr doped YBaCuO thin films

Recent reports on high transient transverse voltages at room temperature in Y1Ba2Cu3O7 (YBCO) thin films exposed to laser irradiation show that the thermoelectric fields transverse to a laser-induced temperature gradient are caused by the nonzero off diagonal elements of the Seebeck tensor. To further enhance these signals of a size approximately 0.1 V/K we used the dependence of the Seebeck coefficient on the in plane thermoelectric properties of YBCO. Thin films with a partial substitution of Y by Pr epitaxially grown on Strontiumtitanate single crystals cut with a tilt angle of 10° between substrate surface and the cubic axis are exposed to UV photon pulses (λ = 248 nm, pulse length 28 ns, fluences 5–200 mJ/cm2) at room temperature. Compared to the undoped films the an enhancement of the signal by a factor of 20 is found for Y0.8Pr0.2Ba2Cu3O7 films. Further increase of the doping level, however, caused a decrease of this peak values. This result is ascribed to the anisotropic changes of the Seebeck tensor matrix components upon doping.