Non-Equilibrium Pathways for Excitation of Bulk and Surface Phonons through Anharmonic Coupling
Fuente:
arXiv
Gespeichert in:
| Hauptverfasser: | , , , , , , , |
|---|---|
| Format: | Preprint |
| Veröffentlicht: |
2023
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1866909130890936320 |
|---|---|
| author | Brand, C. Tinnemann, V. Hanisch-Blicharski, A. Tajik, M. Fortmann, J. D. Kaßen, A. Thiemann, F. Hoegen, M. Horn-von |
| author_facet | Brand, C. Tinnemann, V. Hanisch-Blicharski, A. Tajik, M. Fortmann, J. D. Kaßen, A. Thiemann, F. Hoegen, M. Horn-von |
| contents | Upon impulsive optical excitation of solid-state materials, the non-equilibrium flow of energy from the excited electronic system to the lattice degrees of freedom typically happens in a few picoseconds. Here we identified the surface of thin Bi films grown on Si(001) as an additional subsystem which is excited much slower on a 100 ps timescale that is caused by decoupling due to mismatched phonon dispersions relations of bulk and surface. Anharmonic coupling among the phonon systems provides pathways for excitations which exhibits a 1/T-dependence causing a speed-up of surface excitation at higher temperatures. A quantitative justification is provided by phonon Umklapp processes from lattice thermal conductivity of the Bi bulk. Three-temperature model simulations reveal a pronounced non-equilibrium situation up to nanoseconds: initially, the surface is colder than the bulk, that situation is then inverted during cooling and the surface feeds energy back into the bulk phonon system. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_15740 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Non-Equilibrium Pathways for Excitation of Bulk and Surface Phonons through Anharmonic Coupling Brand, C. Tinnemann, V. Hanisch-Blicharski, A. Tajik, M. Fortmann, J. D. Kaßen, A. Thiemann, F. Hoegen, M. Horn-von Mesoscale and Nanoscale Physics Upon impulsive optical excitation of solid-state materials, the non-equilibrium flow of energy from the excited electronic system to the lattice degrees of freedom typically happens in a few picoseconds. Here we identified the surface of thin Bi films grown on Si(001) as an additional subsystem which is excited much slower on a 100 ps timescale that is caused by decoupling due to mismatched phonon dispersions relations of bulk and surface. Anharmonic coupling among the phonon systems provides pathways for excitations which exhibits a 1/T-dependence causing a speed-up of surface excitation at higher temperatures. A quantitative justification is provided by phonon Umklapp processes from lattice thermal conductivity of the Bi bulk. Three-temperature model simulations reveal a pronounced non-equilibrium situation up to nanoseconds: initially, the surface is colder than the bulk, that situation is then inverted during cooling and the surface feeds energy back into the bulk phonon system. |
| title | Non-Equilibrium Pathways for Excitation of Bulk and Surface Phonons through Anharmonic Coupling |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2310.15740 |