Heat Transport without Heating?—An Ultrafast X‐Ray Perspective into a Metal Heterostructure

Abstract: When the spatial dimensions of metallic heterostructures shrink below the mean free path of its conduction electrons, the transport of electrons and hence the transport of thermal energy by electrons continuously changes from diffusive to ballistic. Electron–phonon coupling sets the mean free path to the nanoscale and the time for equilibration of electron and lattice temperatures to the picosecond range. A particularly intriguing situation occurs in trilayer heterostructures combining metals with very different electron–phonon coupling strength: Heat energy deposited in few atomic layers of Pt is transported into a nanometric Ni film, which is heated more than the Cu film through which the heat is released. Femtosecond pump‐probe experiments with hard X‐ray pulses provide a layer‐specific probe of the heat energy. A purely diffusive two‐temperature model with increased thermal conductivity of hot electrons excellently reproduces the observed signals from all three layers. At the time when the Ni lattice is maximally heated, no significant heat has entered the Cu lattice. This phenomenon would be enhanced in thinner layers where ballistic transport dominates. In this context it is shown that purely diffusive transport can lead to a linear time‐to‐length dependence that must not be misinterpreted as ballistic transport.

Standort
Deutsche Nationalbibliothek Frankfurt am Main
Umfang
Online-Ressource
Sprache
Englisch

Erschienen in
Heat Transport without Heating?—An Ultrafast X‐Ray Perspective into a Metal Heterostructure ; volume:30 ; number:46 ; year:2020 ; extent:8
Advanced functional materials ; 30, Heft 46 (2020) (gesamt 8)

Urheber
Pudell, Jan‐Etienne
Mattern, Maximilian
Hehn, Michel
Malinowski, Grégory
Herzog, Marc
Bargheer, Matias

DOI
10.1002/adfm.202004555
URN
urn:nbn:de:101:1-2022061511333548371093
Rechteinformation
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Letzte Aktualisierung
15.08.2025, 07:40 MESZ

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Beteiligte

  • Pudell, Jan‐Etienne
  • Mattern, Maximilian
  • Hehn, Michel
  • Malinowski, Grégory
  • Herzog, Marc
  • Bargheer, Matias

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