2020/06/14 by Sergiu Ruta, Ruta, Sergiu, Zuwei Fu +7
Materials Science · Physics and Astronomy · #Diamond and Carbon-based Materials Research #FOS: Physical sciences #Magnetic properties of thin films #Materials Science (cond-mat.mtrl-sci) #Mechanical and Optical Resonators
paper · pdf · doi:10.48550/arxiv.2006.07935
openalex publication_date 2020/06/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this work, we present evidence for the existence of a magnonic current on\nthe sub-picosecond time-scale in a ferrimagnetic bilayer and its effect on\nultrafast spin dynamics. The ferrimagnet, GdFeCo, is a material known to\nundergo ultrafast switching within 1-2ps after excitation with femtosecond\nlaser pulses. Here, we show that the strong thermal gradients induced by\napplying femtosecond laser pulses and the presence of chemical inhomogeneities\nlead to local imbalances in the effective temperatures of the spins that\nproduces a rapid transfer of spin angular momentum, which we interpret as an\nultrafast spin Seebeck effect. We have quantified the typical magnon\npropagation in such a system. The results show ballistic magnon propagation\nwith 30nm/ps velocities. The characteristic time scale of such magnon\npropagation indicates that this magnon transport can play an important role in\nswitching, a crucial piece of understanding towards realising next generation\ndata processing devices that operate at much higher frequencies.\n