Thermally induced magnetization dynamics of optically excited YIG/Cu/Ni81Fe19 trilayers
| Autor: | U. A. S. Al-Jarah, B. J. Hickey, R. A. J. Valkass, R. J. Hicken, H. J. Mohamad, Mustafa M. Aziz, L. R. Shelford, R. Al-Saigh, S. Marmion |
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| Rok vydání: | 2017 |
| Předmět: |
Magnetization dynamics
Materials science Condensed matter physics Demagnetizing field 02 engineering and technology 021001 nanoscience & nanotechnology Transient temperature 01 natural sciences Magnetization Reference sample Excited state 0103 physical sciences 010306 general physics 0210 nano-technology Spin (physics) Excitation |
| Zdroj: | Physical Review B. 96 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | The response of ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}\text{/}\mathrm{Cu}\text{/}{\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ trilayer structures to excitation by a femtosecond laser pulse has been studied in optical pump-probe experiments and compared with the response of ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YIG) and ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ reference samples. The optical pump induces a partial demagnetization of the ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$, a large thermal gradient within the YIG, and temperature differences across the interfaces within the sample stack. When a moderate magnetic field is applied close to normal to the sample plane, so as to quasialign the YIG magnetization with the field and cant the ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ magnetization from the plane, ultrafast demagnetization initiates precession of the ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ magnetization. The transient temperature profile within the samples has been modeled using a one-dimensional finite-element computational model of heat conduction, while the magnetization dynamics are well described by a macrospin solution of the Landau-Lifshitz-Gilbert equation. The precessional response of the ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ layers within the trilayers and the ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ reference sample are very similar for pump fluences of up to $1.5\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/\mathrm{c}{\mathrm{m}}^{2}$, beyond which irreversible changes to the magnetic properties of the films are observed. These results suggest that the spin Seebeck effect is ineffective in modifying the precessional dynamics of the present $\mathrm{YIG}\text{/}\mathrm{Cu}\text{/}{\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ samples when subject to ultrafast optical excitation. |
| Databáze: | OpenAIRE |
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