Abstract
Photoinduced transition of the electronic structure of metallic–SmS and Sm3S4 thin films, in which Sm ions possess divalent and trivalent mixed state, have been investigated using a femtosecond laser pulse. Both metallic–SmS and Sm3S4 thin films were prepared by rf magnetron sputtering method. The lattice constants of metallic–SmS and Sm3S4 films, measured by x–ray diffraction method, were 5.705±0.014 Å and 8.521±0.002 Å, respectively. The irradiation experiments were performed using a regeneratively amplified mode–locked Ti:sapphire laser at 800 nm with a pulse duration of 120 fs and a repetition rate of 10 Hz. The Sm3S4 film showed no change when irradiated. In contrast, the irradiated metallic–SmS film showed the significant changes in reflectance and lattice constant due to 4f–5d electronic transition.
