Instantaneous Reflectivity of Tb_0.27Dy_0.73Fe₂ Films Excited by Femtosecond Laser at Different States

The effects of pump power and annealed at 550 ℃ on the instantaneous reflectivity of Tb0.27Dy0.73Fe2 films was studied by femtosecond laser pump-probe technology for improving the characteristics of the materials.The results show that the instantaneous reflectivity ΔR/R curves of unannealed film had four stages,first the reflectivity arrived at the maximum after 200.1 fs excited by femtosecond laser,and then the system was in equilibrium after 200.1 fs.ΔR/R curves of annealed film started to decrease at zero,and then arrived equilibrium after 200.1 fs.With the increasing of pump power the change extent of ΔR/R curve was linear.