Comparative Study of Femtosecond Laser-Induced Ultrafast Magnetization Dynamics in Soft Ferromagnetic Ultra-thin alloy
S. M. Hosseini, F. Jahangiri, R. Jalilian, S. M. Hamidi
The typical demagnetization mechanism is applicable in magneto-optic recording systems on a nanoseconds timescale. Interest in this area has expanded rapidly since understanding the physics of ultrafast magnetization processes by experiment are an acutely challenging task. As a result, in order to explain the quenching of magnetization by laser heating in ferromagnetic alloys such as permalloy, we executed a new theoretical study on permalloy, as well as Ni and Fe ultra-thin films with thickness varying from 1 nm to 5 nm. In particular, we demonstrate that the magnetization decays in a timescale of about 0.1 picoseconds by the microscopic three-temperature model. Our free electron model-based theoretical model represents that electron-phonon coupling coefficient and demagnetization time in the thin-films are strongly sensitive to film thickness, pulse duration and laser fluence, respectively. In particular, we show that the rapid demagnetization (100 fs) is due to electron-magnon excitation. This feature improves data processing speed in communication systems and the recording industry.
