Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems
Ultrafast structural probing has greatly enhanced our understanding of the coupling of atomic motion to electronic and phononic degrees-of-freedom in quasi-bulk materials. In bi- and multilayer model systems, additionally, spatially inhomogeneous relaxation channels are accessible, often governed by...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC and ACA
2021-05-01
|
| Series: | Structural Dynamics |
| Online Access: | http://dx.doi.org/10.1063/4.0000079 |
| _version_ | 1819122414038024192 |
|---|---|
| author | N. Bach S. Schäfer |
| author_facet | N. Bach S. Schäfer |
| author_sort | N. Bach |
| collection | DOAJ |
| description | Ultrafast structural probing has greatly enhanced our understanding of the coupling of atomic motion to electronic and phononic degrees-of-freedom in quasi-bulk materials. In bi- and multilayer model systems, additionally, spatially inhomogeneous relaxation channels are accessible, often governed by pronounced interfacial couplings and local excitations in confined geometries. Here, we systematically explore the key dependencies of the low-frequency acoustic phonon spectrum in an elastically mismatched metal/semiconductor bilayer system optically excited by femtosecond laser pulses. We track the spatiotemporal strain wave propagation in the heterostructure employing a discrete numerical linear chain simulation and access acoustic wave reflections and interfacial couplings with a phonon mode description based on a continuum mechanics model. Due to the interplay of elastic properties and mass densities of the two materials, acoustic resonance frequencies of the heterostructure significantly differ from breathing modes in monolayer films. For large acoustic mismatch, the spatial localization of phonon eigenmodes is derived from analytical approximations and can be interpreted as harmonic oscillations in decoupled mechanical resonators. |
| first_indexed | 2024-12-22T06:52:04Z |
| format | Article |
| id | doaj.art-15d561a9925a41b48b91d9721137b419 |
| institution | Directory Open Access Journal |
| issn | 2329-7778 |
| language | English |
| last_indexed | 2024-12-22T06:52:04Z |
| publishDate | 2021-05-01 |
| publisher | AIP Publishing LLC and ACA |
| record_format | Article |
| series | Structural Dynamics |
| spelling | doaj.art-15d561a9925a41b48b91d9721137b4192022-12-21T18:35:06ZengAIP Publishing LLC and ACAStructural Dynamics2329-77782021-05-0183035101035101-710.1063/4.0000079Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systemsN. Bach0S. Schäfer1Institute of Physics, University of Oldenburg, 26129 Oldenburg, GermanyInstitute of Physics, University of Oldenburg, 26129 Oldenburg, GermanyUltrafast structural probing has greatly enhanced our understanding of the coupling of atomic motion to electronic and phononic degrees-of-freedom in quasi-bulk materials. In bi- and multilayer model systems, additionally, spatially inhomogeneous relaxation channels are accessible, often governed by pronounced interfacial couplings and local excitations in confined geometries. Here, we systematically explore the key dependencies of the low-frequency acoustic phonon spectrum in an elastically mismatched metal/semiconductor bilayer system optically excited by femtosecond laser pulses. We track the spatiotemporal strain wave propagation in the heterostructure employing a discrete numerical linear chain simulation and access acoustic wave reflections and interfacial couplings with a phonon mode description based on a continuum mechanics model. Due to the interplay of elastic properties and mass densities of the two materials, acoustic resonance frequencies of the heterostructure significantly differ from breathing modes in monolayer films. For large acoustic mismatch, the spatial localization of phonon eigenmodes is derived from analytical approximations and can be interpreted as harmonic oscillations in decoupled mechanical resonators.http://dx.doi.org/10.1063/4.0000079 |
| spellingShingle | N. Bach S. Schäfer Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems Structural Dynamics |
| title | Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| title_full | Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| title_fullStr | Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| title_full_unstemmed | Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| title_short | Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| title_sort | ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems |
| url | http://dx.doi.org/10.1063/4.0000079 |
| work_keys_str_mv | AT nbach ultrafaststrainpropagationandacousticresonancesinnanoscalebilayersystems AT sschafer ultrafaststrainpropagationandacousticresonancesinnanoscalebilayersystems |