Micromagnetic Modeling of All-Optical Switching

The control of the magnetization at the microscale by pure optical means is fundamentally interesting and promises faster speeds for data storage devices. Although several experiments have shown that it is possible to locally reverse the magnetization of a ferromagnetic system by means of laser pulses, a completely theoretical description of these all-optical switching (AOS) processes is still lacking. Here, we develop an advanced micromagnetic solver that is applied to the numerical study of the AOS. The solver is based on the Landau-Lifshitz-Bloch equation that governs the dynamics of the magnetization coupled the microscopic three-temperature model, which describes the temporal evolution of the temperatures of the subsystems as caused by laser heating. The helicity-dependent magnetization switching is evaluated by a magnetooptical effective field caused by the inverse Faraday effect when a circularly polarized laser is applied to the sample. All the other usual terms of a full micromagnetic model are included (exchange, anisotropy, and Dzyaloshinskii-Moriya interaction). As a test, the model is used to describe the local magnetization switching of thin-film samples with high perpendicular anisotropy. The results are in a good agreement with available experimental observations.