Proceedings PaperUltrafast magnetization dynamics and spin transport in nano-sized materials: recent theoretical progress (Conference Presentation)
Ultrafast laser-induced demagnetization was discovered two decades ago, however, the underlying fundamental processes of the fast magnetization dissipation continues to be intensively debated. I shall review recent achievements in the field of ultrafast magnetism with a focus on the various proposed mechanisms and on technological relevant applications, such as THz spintronics. Ultrafast demagnetization of a ferromagnetic (FM) layer on a nonmagnetic (NM) metallic layer can cause injection of a large, ultrafast spin-polarized current into the NM layer, which can lead to a strong THz emission pulse. We quantify the amount of spin injection and find that the spin injection proceeds within femtoseconds. Studying a FM/NM/FM trilayer with orthonormal directions of the magnetization in the FM layers, we investigate how the emitted spin current pulse can excite THz spin waves in the 2nd FM layer. Investigating further ultrafast demagnetization and all-optical switching of high-anisotropy materials such as FePt we find that element-dependent spin dynamics plays a role in the picosecond demagnetization, and that ultrafast spin transport can enhance the demagnetization of nano-sized materials. This work was performed together with P. Maldonado, M. Berritta, R. Mondal, K. Carva, L. Salemi, U. Ritzmann, J. Hurst and P. Balaz.