Phonon‐Dominated Energy Transport in Purely Metallic Heterostructures. (15th August 2022)

• Record Type: Journal Article
• Authors: Herzog, Marc; von Reppert, Alexander; Pudell, Jan‐Etienne; Henkel, Carsten; Kronseder, Matthias; Back, Christian H.; Maznev, Alexei A.; Bargheer, Matias
• Is Part Of: Advanced functional materials. Volume 32:Number 41(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-15
• Subjects: heterostructures -- nanoscale energy transports -- non‐equilibrium -- thermal transports -- ultrafast phenomena; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202206179
• Languages: English
• ISSNs: 1616-301X

Abstract

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. Abstract : Researchers in various branches of physical sciences assume that electrons are the main carriers of thermal energy in metals. Here, ultrafast X‐ray diffraction quantifies energy transport in metallic nanoscale heterostructures. Modeling the data with two‐temperature models that describe the non‐equilibrium of electrons and phonons shows that phonons dominate the heat transport within gold films thinner than ≈10 nm.