Prof. Satoshi Iihama
Department of Materials Physics, Nagoya University, Japan
Date & Time: 14:00 - 15:00, May 28th (Wed), 2025.
Place: 2nd Conference Room, Main Bldg., Sengen.
Quantitative measurement of photonic spin torque in ferromagnetic thin films
Prof. Satoshi Iihama
Department of Materials Physics, Nagoya University, Japan
Abstract:
It has been demonstrated during the last decade that magnetization direction of thin film metallic ferromagnets can be controlled by light-helicity referred to as all-optical helicity-dependent switching (AO-HDS) [1-3]. The mechanism of AO-HDS has been discussed as mainly attributed to helicity-dependent heating effect due to magnetic circular dichroism, which leads to stochastic slow time-scale of magnetization switching. Also, the other mechanism such as transfer of photonic angular momentum to magnetization has been discussed, which might be a small effect but promising towards ultrafast optical manipulation of magnetization. Recently, magnetization dynamics induced by ultrafast photonic spin torque has been reported in ferromagnetic thin films and ferromagnet/ heavy metal heterostructures [4-8]. Circularlypolarized light induced magnetization dynamics measurement enables us to quantify photonic angular momentum transfer torque on magnetization. The angular momentum conversion efficiency from photon to magnetization in ferromagnets will be discussed in the presentation.
[1] C. H. Lambert et al., Science 345, 1337 (2014).
[2] Y. K. Takahashi et al., Phys. Rev. Appl. 6, 054004 (2016).
[3] R. John et al., Sci. Rep. 7, 4114 (2017).
[4] G. M. Choi et al., Nat. Commun. 8, 15085 (2017).
[5] G. M. Choi et al., Nat. Commun. 11, 1482 (2020).
[6] S. Iihama et al., Nanophotonics 10, 1169 (2020).
[7] S. Iihama et al., J. Appl. Phys. 131, 023901 (2022).
[8] K. Nukui, S. I. et al., Phys. Rev. Lett. 134, 016701 (2025).
[1] C. H. Lambert et al., Science 345, 1337 (2014).
[2] Y. K. Takahashi et al., Phys. Rev. Appl. 6, 054004 (2016).
[3] R. John et al., Sci. Rep. 7, 4114 (2017).
[4] G. M. Choi et al., Nat. Commun. 8, 15085 (2017).
[5] G. M. Choi et al., Nat. Commun. 11, 1482 (2020).
[6] S. Iihama et al., Nanophotonics 10, 1169 (2020).
[7] S. Iihama et al., J. Appl. Phys. 131, 023901 (2022).
[8] K. Nukui, S. I. et al., Phys. Rev. Lett. 134, 016701 (2025).