Laser-induced ultrafast photovoltaic effect in La0.67Ca0.33MnO3 films at room temperature

Pulsed laser-induced ultrafast photovoltaic effects have been investigated in La0.67Ca0.33MnO3 films on tilted SrTiO3 substrates fabricated by laser molecular beam epitaxy. A picosecond (ps) photovoltaic pulse without any applied bias to the film has been observed at room temperature. The rise time and full-width at half-maximum of the photovoltaic pulse are as short as 300 and 700 ps, respectively when the film has been irradiated by a laser pulse of 25 ps duration and 1.064 μm wavelength. The photovoltage sensitivity is as large as 0.45 V/mJ, and the photocurrent sensitivity is more than 0.25 A/mJ. The mechanism is proposed as the combination of a photoelectron and a Seebeck processes, and the Seebeck coefficient we obtained, ∼4.04 μV/K, is one order larger than previous report.