Effect of Femtosecond Laser Pulse Irradiation on the Electronic Structure of Samarium Sulfide Thin Films

抄録

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.