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| Format: | Preprint |
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2025
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| Online-Zugang: | https://arxiv.org/abs/2512.17565 |
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| _version_ | 1866912776855748608 |
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| author | Jarecki, Jasmin Mehner, Lisa Mattern, Maximilian Jurgilaitis, Andrius Zeuschner, Steffen Peer Ahn, Byungnam Baltrusch, Florian Ekström, J. Carl Kroon, David Herzog, Marc Walz, Constantin Weber, Fried-Conrad Larsson, Jörgen Hehn, Michel Pudell, Jan-Etienne Schick, Daniel von Reppert, Alexander Bargheer, Matias |
| author_facet | Jarecki, Jasmin Mehner, Lisa Mattern, Maximilian Jurgilaitis, Andrius Zeuschner, Steffen Peer Ahn, Byungnam Baltrusch, Florian Ekström, J. Carl Kroon, David Herzog, Marc Walz, Constantin Weber, Fried-Conrad Larsson, Jörgen Hehn, Michel Pudell, Jan-Etienne Schick, Daniel von Reppert, Alexander Bargheer, Matias |
| contents | When the dimensions of structures shrink to the order of the inelastic mean free path of the energy-carrying quasi-particles, the character of energy transport changes from diffusive to ballistic. However, the point of transition remains a matter of debate. Here, we determine the dominant channel of energy transport through a nanoscale Cu layer as a function of its thickness. The energy rapidly transferred across Cu via hot electrons from a photo-excited Pt layer into a buried Ni detection layer translates into a rapid expansion of the Ni layer probed via ultrafast x-ray diffraction. The non-linear dependence of the Ni strain amplitude on the absorbed laser fluence indicates that the transport through Cu becomes more efficient with increasing fluence. This fluence-dependent transport efficiency is reproduced by a diffusive energy transport model and serves as a generally applicable experimental approach to distinguish diffusion from ballistic transport. Following this approach, we identify diffusive electronic energy transport to govern the spatial energy distribution for Cu layer thicknesses larger than twice the electronic inelastic mean free path. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_17565 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Experimental evidence of dominant ultrafast diffusive energy transport by hot electrons in Cu Jarecki, Jasmin Mehner, Lisa Mattern, Maximilian Jurgilaitis, Andrius Zeuschner, Steffen Peer Ahn, Byungnam Baltrusch, Florian Ekström, J. Carl Kroon, David Herzog, Marc Walz, Constantin Weber, Fried-Conrad Larsson, Jörgen Hehn, Michel Pudell, Jan-Etienne Schick, Daniel von Reppert, Alexander Bargheer, Matias Materials Science When the dimensions of structures shrink to the order of the inelastic mean free path of the energy-carrying quasi-particles, the character of energy transport changes from diffusive to ballistic. However, the point of transition remains a matter of debate. Here, we determine the dominant channel of energy transport through a nanoscale Cu layer as a function of its thickness. The energy rapidly transferred across Cu via hot electrons from a photo-excited Pt layer into a buried Ni detection layer translates into a rapid expansion of the Ni layer probed via ultrafast x-ray diffraction. The non-linear dependence of the Ni strain amplitude on the absorbed laser fluence indicates that the transport through Cu becomes more efficient with increasing fluence. This fluence-dependent transport efficiency is reproduced by a diffusive energy transport model and serves as a generally applicable experimental approach to distinguish diffusion from ballistic transport. Following this approach, we identify diffusive electronic energy transport to govern the spatial energy distribution for Cu layer thicknesses larger than twice the electronic inelastic mean free path. |
| title | Experimental evidence of dominant ultrafast diffusive energy transport by hot electrons in Cu |
| topic | Materials Science |
| url | https://arxiv.org/abs/2512.17565 |