Of Lcmo And Ybco Thin Films, Time-varying Laser-induced Voltage

The laser induced thermoelectric voltage effect had been found in LCMO and YBCO thin films grown on tilted substrates due to heating by laser radiation. We make use of a micro-cell network model and a planar heat source, based on the atomic layer thermopile model, to obtain a time-dependence formula of the effect. From the fitting of the measured curve, we obtained D = 7.81 x 109 m2/s, 8= 96.82 nm, Sab -S = 0.22 yV/K, and Dis the thermal diffusion constant, 8 is the penetration depth of the laser radiation with 1064-nm wavelength, Sab-S is the difference of Seebeck coefficient of the thin film. The influence of the parameters such as D and d(illm thickness) on laser induced voltage had been discussed. The linear relation between the peak voltage and the laser energy per pulse had been deduced from the formula. Basing on the linear relation, we designed laser energy/power meter. A fitting curve between the decay time constant and the film thickness of YBCO was obtained, and the film thickness can be obtained from the fitting.Graduate student: Zhang Guo-yongMajor: Material Science Directed by: Zhang Peng-xiang...