Element-selectively tracking ultrafast demagnetization process in Co/Pt multilayer thin films by the resonant magneto-optical Kerr effect
Kohei Yamamoto, Souliman El Moussaoui, Yasuyuki Hirata, Susumu Yamamoto, Yuya Kubota, Shigeki Owada, Makina Yabashi, Takeshi Seki, Koki Takanashi, Iwao Matsuda, Hiroki Wadati
Abstract
We examined the photo-induced dynamics of ferromagnetic Co/Pt thin films exhibiting perpendicular magnetic anisotropy by means of the resonant polar magneto-optical Kerr effect with element specificity. The investigation was conducted at Pt N6,7 and Co M2,3 edges using an x-ray free electron laser. The obtained results showed a clear element dependence of photo-induced demagnetization time scales: τdemag.Co=80±60 fs and τdemag.Pt=640±140 fs. This dependence is explained by the induced moment of the Pt atom by current flow from the Co layer through the interfaces. The observed magnetization dynamics can be attributed to the characteristics of photo-induced Co/Pt thin film phenomena including all-optical switching.