The indispensable role of the transversal spin fluctuations mechanism in laser-induced demagnetization of Co/Pt multilayers with nanoscale magnetic domains

Wei Zhang*, Wei He, Li Cong Peng, Ying Zhang, Jian Wang Cai, Richard F.L. Evans, Xiang Qun Zhang, Zhao Hua Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The switching of magnetic domains induced by an ultrashort laser pulse has been demonstrated in nanostructured ferromagnetic films. This leads to the dawn of a new era in breaking the ultimate physical limit for the speed of magnetic switching and manipulation, which is relevant to current and future information storage. However, our understanding of the interactions between light and spins in magnetic heterostructures with nanoscale domain structures is still lacking. Here, both time-resolved magneto-optical Kerr effect experiments and atomistic simulations are carried out to investigate the dominant mechanism of laser-induced ultrafast demagnetization in [Co/Pt]20 multilayers with nanoscale magnetic domains. It is found that the ultrafast demagnetization time remains constant with various magnetic configurations, indicating that the domain structures play a minor role in laser-induced ultrafast demagnetization. In addition, both in experiment and atomistic simulations, we find a dependence of ultrafast demagnetization time τ M on the laser fluence, which is in contrast to the observations of spin transport within magnetic domains. The remarkable agreement between experiment and atomistic simulations indicates that the local dissipation of spin angular momentum is the dominant demagnetization mechanism in this system. More interestingly, we made a comparison between the atomistic spin dynamic simulation and the longitudinal spin flip model, highlighting that the transversal spin fluctuations mechanism is responsible for the ultrafast demagnetization in the case of inhomogeneous magnetic structures. This is a significant advance in clarifying the microscopic mechanism underlying the process of ultrafast demagnetization in inhomogeneous magnetic structures.

Original languageEnglish
Article number275703
Number of pages9
Issue number27
Early online date12 Apr 2018
Publication statusPublished - 4 May 2018

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  • nanoscale magnetic domains structures
  • ultrafast spin dynamics

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