Indirect heating of Pt by short-pulse laser irradiation of Au in a nanoscale Pt/Au bilayer

Thermal transport in a metallic multilayer on picosecond time scales is controlled by the electronic thermal conductivity (Lambda(e)), the electronic interfacial thermal conductance (G(ee)), and electron-phonon coupling constant (g). We analyze heat transfer in a nanoscale Pt/Au bilayer using data obtained in pump-probe measurements and modeling using a transmission-line-equivalent circuit. For optical exciation of either the Pt or Au side of the bilayer, the majority of energy is deposited into the Pt phonons on a time scale of approximate to 1 ps because g(Pt) >> g(Au) and G(ee) > g(Au)h(Au), where h(Au) is the thickness of the Au layer. We determine g of the Au layer and set a lower bound on G(ee) of the Pt/Au interface: g(Au) = 2.2 +/- 0.6 x 10(16) Wm(-3) K-1 and G(ee) > 5 GWm(-2) K-1.