Element-specific ultrafast lattice dynamics in FePt nanoparticles
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arXiv
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2024
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| author | Turenne, Diego Vaskivskiy, Igor Sokolowski-Tinten, Klaus Wang, Xijie Reid, Alexander H. Shen, Xiaoshe Lin, Ming-Fu Park, Suji Weathersby, Stephen Kozina, Michael Hoffmann, Matthias Wang, Jian Sebesta, Jakub Takahashi, Yukiko K. Grånäs, Oscar Oppeneer, Peter Dürr, Hermann A. |
| author_facet | Turenne, Diego Vaskivskiy, Igor Sokolowski-Tinten, Klaus Wang, Xijie Reid, Alexander H. Shen, Xiaoshe Lin, Ming-Fu Park, Suji Weathersby, Stephen Kozina, Michael Hoffmann, Matthias Wang, Jian Sebesta, Jakub Takahashi, Yukiko K. Grånäs, Oscar Oppeneer, Peter Dürr, Hermann A. |
| contents | Light-matter interaction at the nanoscale in magnetic alloys and heterostructures is a topic of intense research in view of potential applications in high-density magnetic recording. While the element-specific dynamics of electron spins is directly accessible to resonant x-ray pulses with femtosecond time structure, the possible element-specific atomic motion remains largely unexplored. We use ultrafast electron diffraction to probe the temporal evolution of lattice Bragg peaks of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse. The diffraction interference between Fe and Pt sublattices enables us to demonstrate that the Fe mean-square vibration amplitudes are significantly larger that those of Pt as expected from their different atomic mass. Both are found to increase as energy is transferred from the laser-excited electrons to the lattice. Contrary to this intuitive behavior, we observe a laser-induced lattice expansion that is larger for Pt than for Fe atoms during the first picosecond after laser excitation. This effect points to the strain-wave driven lattice expansion with the longitudinal acoustic Pt motion dominating that of Fe. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_04980 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Element-specific ultrafast lattice dynamics in FePt nanoparticles Turenne, Diego Vaskivskiy, Igor Sokolowski-Tinten, Klaus Wang, Xijie Reid, Alexander H. Shen, Xiaoshe Lin, Ming-Fu Park, Suji Weathersby, Stephen Kozina, Michael Hoffmann, Matthias Wang, Jian Sebesta, Jakub Takahashi, Yukiko K. Grånäs, Oscar Oppeneer, Peter Dürr, Hermann A. Materials Science Light-matter interaction at the nanoscale in magnetic alloys and heterostructures is a topic of intense research in view of potential applications in high-density magnetic recording. While the element-specific dynamics of electron spins is directly accessible to resonant x-ray pulses with femtosecond time structure, the possible element-specific atomic motion remains largely unexplored. We use ultrafast electron diffraction to probe the temporal evolution of lattice Bragg peaks of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse. The diffraction interference between Fe and Pt sublattices enables us to demonstrate that the Fe mean-square vibration amplitudes are significantly larger that those of Pt as expected from their different atomic mass. Both are found to increase as energy is transferred from the laser-excited electrons to the lattice. Contrary to this intuitive behavior, we observe a laser-induced lattice expansion that is larger for Pt than for Fe atoms during the first picosecond after laser excitation. This effect points to the strain-wave driven lattice expansion with the longitudinal acoustic Pt motion dominating that of Fe. |
| title | Element-specific ultrafast lattice dynamics in FePt nanoparticles |
| topic | Materials Science |
| url | https://arxiv.org/abs/2404.04980 |