Fig. 3

Magnetization dynamics of Fe and Ni layer in a Fe/Ru/Ni and b Fe/Ta/Ni multilayers. c Kerr vector \(\Phi\) in the complex plane. d Representation of relation that the measured Kerr signal \({S}^{(i)}\) is the projection of Kerr vector \({\Phi }^{(i)}\). e Kerr signal measured at a different detection angle corresponding to Ni or Au layer. Magnetization dynamics of f 10 nm and g 40 nm Co films on their back (B) and front (F) sides. h Calculated ultrafast demagnetization for the Co film with the contribution of both spin flips and spin transport (black line) or only spin transport (blue line). i Time-dependent magneto-optical Kerr signal measured at different Cu thickness. j The time delay of the onset of demagnetization (top) and the characteristic demagnetization time (bottom) as a function of Cu thickness. Figure a and b are reproduced with permission from ref. [62]. Copyright (2010) American Physical Society. Figure c and d are reproduced with permission from ref. [71]. Copyright (2002) American Physical Society. Figure e are reproduced with permission from ref. [66]. Copyright (2017) American Physical Society. Figure f, g, and h are reproduced with permission from ref. [67]. Copyright (2017) American Physical Society. Figure i and j are reproduced with permission from ref. [75]. Copyright (2016) American Physical Society