Herzog, M.; von Reppert, A.; Pudell, J.E.; Henkel, C.; Kronseder, M.; Back, C.H.; Maznev, A.A.; Bargheer, M.: Phonon-Dominated Energy Transport in Purely Metallic Heterostructures. Advanced Functional Materials 32 (2022), p. 2206179/1-8
10.1002/adfm.202206179
Open Access Version
Abstract:
Ultrafast X-ray diffraction is used to quantify the transport of energy in laser-excited nanoscale gold–nickel (Au–Ni) bilayers. Electron transport and efficient electron–phonon coupling in Ni convert the laser-deposited energy in the conduction electrons within a few picoseconds into a strong non-equilibrium between hot Ni and cold Au phonons at the bilayer interface. Modeling of the subsequent equilibration dynamics within various two-temperature models confirms that for ultrathin Au films, the thermal transport is dominated by phonons instead of conduction electrons because of the weak electron–phonon coupling in Au.