We have measured the hot-electron-induced demagnetization of a [Co/Pt] 2 multilayer in M(x nm)/Cu(100 nm)/[Co(0.6 nm)/Pt(1.1 nm)] 2 samples depending on the nature of the capping layer M and its thickness x. We found out that a Pt layer is more efficient than [Co/Pt] X , Cu, or MgO layers in converting infrared (IR) photon pulses into hot-electron pulses at a given laser power. We also found out that the maximum relative demagnetization amplitude is achieved for M(x) ¼ Pt (7 nm). Our experimental results show qualitative agreement with numerical simulations based on the superdiffusive spin transport model. We concluded that the maximum relative demagnetization amplitude, which corresponds to the highest photon conversion into hot electrons, is an interplay between the IR penetration depth and the hot-electron inelastic mean free path within the capping layer.